Initial import.

53 files changed, 9297 insertions, 0 deletions

diff --git a/chromium/base/threading/OWNERS b/chromium/base/threading/OWNERS
new file mode 100644
index 00000000000..4198e99c5cc
--- /dev/null
+++ b/chromium/base/threading/OWNERS
@@ -0,0 +1,2 @@
+# For thread_resrictions.*
+jam@chromium.org
diff --git a/chromium/base/threading/non_thread_safe.h b/chromium/base/threading/non_thread_safe.h
new file mode 100644
index 00000000000..cf7a41818da
--- /dev/null
+++ b/chromium/base/threading/non_thread_safe.h
@@ -0,0 +1,73 @@
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef BASE_THREADING_NON_THREAD_SAFE_H_
+#define BASE_THREADING_NON_THREAD_SAFE_H_
+
+// Classes deriving from NonThreadSafe may need to suppress MSVC warning 4275:
+// non dll-interface class 'Bar' used as base for dll-interface class 'Foo'.
+// There is a specific macro to do it: NON_EXPORTED_BASE(), defined in
+// compiler_specific.h
+#include "base/compiler_specific.h"
+
+// See comment at top of thread_checker.h
+#if (!defined(NDEBUG) || defined(DCHECK_ALWAYS_ON))
+#define ENABLE_NON_THREAD_SAFE 1
+#else
+#define ENABLE_NON_THREAD_SAFE 0
+#endif
+
+#if ENABLE_NON_THREAD_SAFE
+#include "base/threading/non_thread_safe_impl.h"
+#endif
+
+namespace base {
+
+// Do nothing implementation of NonThreadSafe, for release mode.
+//
+// Note: You should almost always use the NonThreadSafe class to get
+// the right version of the class for your build configuration.
+class NonThreadSafeDoNothing {
+ public:
+  bool CalledOnValidThread() const {
+    return true;
+  }
+
+ protected:
+  ~NonThreadSafeDoNothing() {}
+  void DetachFromThread() {}
+};
+
+// NonThreadSafe is a helper class used to help verify that methods of a
+// class are called from the same thread.  One can inherit from this class
+// and use CalledOnValidThread() to verify.
+//
+// This is intended to be used with classes that appear to be thread safe, but
+// aren't.  For example, a service or a singleton like the preferences system.
+//
+// Example:
+// class MyClass : public base::NonThreadSafe {
+//  public:
+//   void Foo() {
+//     DCHECK(CalledOnValidThread());
+//     ... (do stuff) ...
+//   }
+// }
+//
+// Note that base::ThreadChecker offers identical functionality to
+// NonThreadSafe, but does not require inheritence. In general, it is preferable
+// to have a base::ThreadChecker as a member, rather than inherit from
+// NonThreadSafe. For more details about when to choose one over the other, see
+// the documentation for base::ThreadChecker.
+#if ENABLE_NON_THREAD_SAFE
+typedef NonThreadSafeImpl NonThreadSafe;
+#else
+typedef NonThreadSafeDoNothing NonThreadSafe;
+#endif  // ENABLE_NON_THREAD_SAFE
+
+#undef ENABLE_NON_THREAD_SAFE
+
+}  // namespace base
+
+#endif  // BASE_NON_THREAD_SAFE_H_
diff --git a/chromium/base/threading/non_thread_safe_impl.cc b/chromium/base/threading/non_thread_safe_impl.cc
new file mode 100644
index 00000000000..7e729d9ee42
--- /dev/null
+++ b/chromium/base/threading/non_thread_safe_impl.cc
@@ -0,0 +1,23 @@
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "base/threading/non_thread_safe_impl.h"
+
+#include "base/logging.h"
+
+namespace base {
+
+bool NonThreadSafeImpl::CalledOnValidThread() const {
+  return thread_checker_.CalledOnValidThread();
+}
+
+NonThreadSafeImpl::~NonThreadSafeImpl() {
+  DCHECK(CalledOnValidThread());
+}
+
+void NonThreadSafeImpl::DetachFromThread() {
+  thread_checker_.DetachFromThread();
+}
+
+}  // namespace base
diff --git a/chromium/base/threading/non_thread_safe_impl.h b/chromium/base/threading/non_thread_safe_impl.h
new file mode 100644
index 00000000000..a3a356df4a5
--- /dev/null
+++ b/chromium/base/threading/non_thread_safe_impl.h
@@ -0,0 +1,39 @@
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef BASE_THREADING_NON_THREAD_SAFE_IMPL_H_
+#define BASE_THREADING_NON_THREAD_SAFE_IMPL_H_
+
+#include "base/base_export.h"
+#include "base/threading/thread_checker_impl.h"
+
+namespace base {
+
+// Full implementation of NonThreadSafe, for debug mode or for occasional
+// temporary use in release mode e.g. when you need to CHECK on a thread
+// bug that only occurs in the wild.
+//
+// Note: You should almost always use the NonThreadSafe class to get
+// the right version of the class for your build configuration.
+class BASE_EXPORT NonThreadSafeImpl {
+ public:
+  bool CalledOnValidThread() const;
+
+ protected:
+  ~NonThreadSafeImpl();
+
+  // Changes the thread that is checked for in CalledOnValidThread. The next
+  // call to CalledOnValidThread will attach this class to a new thread. It is
+  // up to the NonThreadSafe derived class to decide to expose this or not.
+  // This may be useful when an object may be created on one thread and then
+  // used exclusively on another thread.
+  void DetachFromThread();
+
+ private:
+  ThreadCheckerImpl thread_checker_;
+};
+
+}  // namespace base
+
+#endif  // BASE_THREADING_NON_THREAD_SAFE_IMPL_H_
diff --git a/chromium/base/threading/non_thread_safe_unittest.cc b/chromium/base/threading/non_thread_safe_unittest.cc
new file mode 100644
index 00000000000..8a82a637ab7
--- /dev/null
+++ b/chromium/base/threading/non_thread_safe_unittest.cc
@@ -0,0 +1,167 @@
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "base/basictypes.h"
+#include "base/logging.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/threading/non_thread_safe.h"
+#include "base/threading/simple_thread.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+// Duplicated from base/threading/non_thread_safe.h so that we can be
+// good citizens there and undef the macro.
+#if (!defined(NDEBUG) || defined(DCHECK_ALWAYS_ON))
+#define ENABLE_NON_THREAD_SAFE 1
+#else
+#define ENABLE_NON_THREAD_SAFE 0
+#endif
+
+namespace base {
+
+namespace {
+
+// Simple class to exersice the basics of NonThreadSafe.
+// Both the destructor and DoStuff should verify that they were
+// called on the same thread as the constructor.
+class NonThreadSafeClass : public NonThreadSafe {
+ public:
+  NonThreadSafeClass() {}
+
+  // Verifies that it was called on the same thread as the constructor.
+  void DoStuff() {
+    DCHECK(CalledOnValidThread());
+  }
+
+  void DetachFromThread() {
+    NonThreadSafe::DetachFromThread();
+  }
+
+  static void MethodOnDifferentThreadImpl();
+  static void DestructorOnDifferentThreadImpl();
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(NonThreadSafeClass);
+};
+
+// Calls NonThreadSafeClass::DoStuff on another thread.
+class CallDoStuffOnThread : public SimpleThread {
+ public:
+  explicit CallDoStuffOnThread(NonThreadSafeClass* non_thread_safe_class)
+      : SimpleThread("call_do_stuff_on_thread"),
+        non_thread_safe_class_(non_thread_safe_class) {
+  }
+
+  virtual void Run() OVERRIDE {
+    non_thread_safe_class_->DoStuff();
+  }
+
+ private:
+  NonThreadSafeClass* non_thread_safe_class_;
+
+  DISALLOW_COPY_AND_ASSIGN(CallDoStuffOnThread);
+};
+
+// Deletes NonThreadSafeClass on a different thread.
+class DeleteNonThreadSafeClassOnThread : public SimpleThread {
+ public:
+  explicit DeleteNonThreadSafeClassOnThread(
+      NonThreadSafeClass* non_thread_safe_class)
+      : SimpleThread("delete_non_thread_safe_class_on_thread"),
+        non_thread_safe_class_(non_thread_safe_class) {
+  }
+
+  virtual void Run() OVERRIDE {
+    non_thread_safe_class_.reset();
+  }
+
+ private:
+  scoped_ptr<NonThreadSafeClass> non_thread_safe_class_;
+
+  DISALLOW_COPY_AND_ASSIGN(DeleteNonThreadSafeClassOnThread);
+};
+
+}  // namespace
+
+TEST(NonThreadSafeTest, CallsAllowedOnSameThread) {
+  scoped_ptr<NonThreadSafeClass> non_thread_safe_class(
+      new NonThreadSafeClass);
+
+  // Verify that DoStuff doesn't assert.
+  non_thread_safe_class->DoStuff();
+
+  // Verify that the destructor doesn't assert.
+  non_thread_safe_class.reset();
+}
+
+TEST(NonThreadSafeTest, DetachThenDestructOnDifferentThread) {
+  scoped_ptr<NonThreadSafeClass> non_thread_safe_class(
+      new NonThreadSafeClass);
+
+  // Verify that the destructor doesn't assert when called on a different thread
+  // after a detach.
+  non_thread_safe_class->DetachFromThread();
+  DeleteNonThreadSafeClassOnThread delete_on_thread(
+      non_thread_safe_class.release());
+
+  delete_on_thread.Start();
+  delete_on_thread.Join();
+}
+
+#if GTEST_HAS_DEATH_TEST || !ENABLE_NON_THREAD_SAFE
+
+void NonThreadSafeClass::MethodOnDifferentThreadImpl() {
+  scoped_ptr<NonThreadSafeClass> non_thread_safe_class(
+      new NonThreadSafeClass);
+
+  // Verify that DoStuff asserts in debug builds only when called
+  // on a different thread.
+  CallDoStuffOnThread call_on_thread(non_thread_safe_class.get());
+
+  call_on_thread.Start();
+  call_on_thread.Join();
+}
+
+#if ENABLE_NON_THREAD_SAFE
+TEST(NonThreadSafeDeathTest, MethodNotAllowedOnDifferentThreadInDebug) {
+  ASSERT_DEATH({
+      NonThreadSafeClass::MethodOnDifferentThreadImpl();
+    }, "");
+}
+#else
+TEST(NonThreadSafeTest, MethodAllowedOnDifferentThreadInRelease) {
+  NonThreadSafeClass::MethodOnDifferentThreadImpl();
+}
+#endif  // ENABLE_NON_THREAD_SAFE
+
+void NonThreadSafeClass::DestructorOnDifferentThreadImpl() {
+  scoped_ptr<NonThreadSafeClass> non_thread_safe_class(
+      new NonThreadSafeClass);
+
+  // Verify that the destructor asserts in debug builds only
+  // when called on a different thread.
+  DeleteNonThreadSafeClassOnThread delete_on_thread(
+      non_thread_safe_class.release());
+
+  delete_on_thread.Start();
+  delete_on_thread.Join();
+}
+
+#if ENABLE_NON_THREAD_SAFE
+TEST(NonThreadSafeDeathTest, DestructorNotAllowedOnDifferentThreadInDebug) {
+  ASSERT_DEATH({
+      NonThreadSafeClass::DestructorOnDifferentThreadImpl();
+    }, "");
+}
+#else
+TEST(NonThreadSafeTest, DestructorAllowedOnDifferentThreadInRelease) {
+  NonThreadSafeClass::DestructorOnDifferentThreadImpl();
+}
+#endif  // ENABLE_NON_THREAD_SAFE
+
+#endif  // GTEST_HAS_DEATH_TEST || !ENABLE_NON_THREAD_SAFE
+
+// Just in case we ever get lumped together with other compilation units.
+#undef ENABLE_NON_THREAD_SAFE
+
+}  // namespace base
diff --git a/chromium/base/threading/platform_thread.h b/chromium/base/threading/platform_thread.h
new file mode 100644
index 00000000000..9742d570c6f
--- /dev/null
+++ b/chromium/base/threading/platform_thread.h
@@ -0,0 +1,160 @@
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// WARNING: You should *NOT* be using this class directly.  PlatformThread is
+// the low-level platform-specific abstraction to the OS's threading interface.
+// You should instead be using a message-loop driven Thread, see thread.h.
+
+#ifndef BASE_THREADING_PLATFORM_THREAD_H_
+#define BASE_THREADING_PLATFORM_THREAD_H_
+
+#include "base/base_export.h"
+#include "base/basictypes.h"
+#include "base/time/time.h"
+#include "build/build_config.h"
+
+#if defined(OS_WIN)
+#include <windows.h>
+#elif defined(OS_POSIX)
+#include <pthread.h>
+#include <unistd.h>
+#endif
+
+namespace base {
+
+#if defined(OS_WIN)
+typedef DWORD PlatformThreadId;
+#elif defined(OS_POSIX)
+typedef pid_t PlatformThreadId;
+#endif
+
+class PlatformThreadHandle {
+ public:
+#if defined(OS_WIN)
+  typedef void* Handle;
+#elif defined(OS_POSIX)
+  typedef pthread_t Handle;
+#endif
+
+  PlatformThreadHandle()
+      : handle_(0),
+        id_(0) {
+  }
+
+  explicit PlatformThreadHandle(Handle handle)
+      : handle_(handle),
+        id_(0) {
+  }
+
+  PlatformThreadHandle(Handle handle,
+                       PlatformThreadId id)
+      : handle_(handle),
+        id_(id) {
+  }
+
+  bool is_equal(const PlatformThreadHandle& other) {
+    return handle_ == other.handle_;
+  }
+
+  bool is_null() {
+    return !handle_;
+  }
+
+  Handle platform_handle() {
+    return handle_;
+  }
+
+ private:
+  friend class PlatformThread;
+
+  Handle handle_;
+  PlatformThreadId id_;
+};
+
+const PlatformThreadId kInvalidThreadId(0);
+
+// Valid values for SetThreadPriority()
+enum ThreadPriority{
+  kThreadPriority_Normal,
+  // Suitable for low-latency, glitch-resistant audio.
+  kThreadPriority_RealtimeAudio,
+  // Suitable for threads which generate data for the display (at ~60Hz).
+  kThreadPriority_Display,
+  // Suitable for threads that shouldn't disrupt high priority work.
+  kThreadPriority_Background
+};
+
+// A namespace for low-level thread functions.
+class BASE_EXPORT PlatformThread {
+ public:
+  // Implement this interface to run code on a background thread.  Your
+  // ThreadMain method will be called on the newly created thread.
+  class BASE_EXPORT Delegate {
+   public:
+    virtual void ThreadMain() = 0;
+
+   protected:
+    virtual ~Delegate() {}
+  };
+
+  // Gets the current thread id, which may be useful for logging purposes.
+  static PlatformThreadId CurrentId();
+
+  // Get the current handle.
+  static PlatformThreadHandle CurrentHandle();
+
+  // Yield the current thread so another thread can be scheduled.
+  static void YieldCurrentThread();
+
+  // Sleeps for the specified duration.
+  static void Sleep(base::TimeDelta duration);
+
+  // Sets the thread name visible to debuggers/tools. This has no effect
+  // otherwise. This name pointer is not copied internally. Thus, it must stay
+  // valid until the thread ends.
+  static void SetName(const char* name);
+
+  // Gets the thread name, if previously set by SetName.
+  static const char* GetName();
+
+  // Creates a new thread.  The |stack_size| parameter can be 0 to indicate
+  // that the default stack size should be used.  Upon success,
+  // |*thread_handle| will be assigned a handle to the newly created thread,
+  // and |delegate|'s ThreadMain method will be executed on the newly created
+  // thread.
+  // NOTE: When you are done with the thread handle, you must call Join to
+  // release system resources associated with the thread.  You must ensure that
+  // the Delegate object outlives the thread.
+  static bool Create(size_t stack_size, Delegate* delegate,
+                     PlatformThreadHandle* thread_handle);
+
+  // CreateWithPriority() does the same thing as Create() except the priority of
+  // the thread is set based on |priority|.  Can be used in place of Create()
+  // followed by SetThreadPriority().  SetThreadPriority() has not been
+  // implemented on the Linux platform yet, this is the only way to get a high
+  // priority thread on Linux.
+  static bool CreateWithPriority(size_t stack_size, Delegate* delegate,
+                                 PlatformThreadHandle* thread_handle,
+                                 ThreadPriority priority);
+
+  // CreateNonJoinable() does the same thing as Create() except the thread
+  // cannot be Join()'d.  Therefore, it also does not output a
+  // PlatformThreadHandle.
+  static bool CreateNonJoinable(size_t stack_size, Delegate* delegate);
+
+  // Joins with a thread created via the Create function.  This function blocks
+  // the caller until the designated thread exits.  This will invalidate
+  // |thread_handle|.
+  static void Join(PlatformThreadHandle thread_handle);
+
+  static void SetThreadPriority(PlatformThreadHandle handle,
+                                ThreadPriority priority);
+
+ private:
+  DISALLOW_IMPLICIT_CONSTRUCTORS(PlatformThread);
+};
+
+}  // namespace base
+
+#endif  // BASE_THREADING_PLATFORM_THREAD_H_
diff --git a/chromium/base/threading/platform_thread_android.cc b/chromium/base/threading/platform_thread_android.cc
new file mode 100644
index 00000000000..28026350b66
--- /dev/null
+++ b/chromium/base/threading/platform_thread_android.cc
@@ -0,0 +1,105 @@
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "base/threading/platform_thread.h"
+
+#include <errno.h>
+#include <sys/resource.h>
+
+#include "base/android/jni_android.h"
+#include "base/android/thread_utils.h"
+#include "base/lazy_instance.h"
+#include "base/logging.h"
+#include "base/threading/thread_id_name_manager.h"
+#include "base/tracked_objects.h"
+#include "jni/ThreadUtils_jni.h"
+
+namespace base {
+
+namespace {
+int ThreadNiceValue(ThreadPriority priority) {
+  // These nice values are taken from Android, which uses nice
+  // values like linux, but defines some preset nice values.
+  //   Process.THREAD_PRIORITY_AUDIO = -16
+  //   Process.THREAD_PRIORITY_BACKGROUND = 10
+  //   Process.THREAD_PRIORITY_DEFAULT = 0;
+  //   Process.THREAD_PRIORITY_DISPLAY = -4;
+  //   Process.THREAD_PRIORITY_FOREGROUND = -2;
+  //   Process.THREAD_PRIORITY_LESS_FAVORABLE = 1;
+  //   Process.THREAD_PRIORITY_LOWEST = 19;
+  //   Process.THREAD_PRIORITY_MORE_FAVORABLE = -1;
+  //   Process.THREAD_PRIORITY_URGENT_AUDIO = -19;
+  //   Process.THREAD_PRIORITY_URGENT_DISPLAY = -8;
+  // We use -6 for display, but we may want to split this
+  // into urgent (-8) and non-urgent (-4).
+  static const int threadPriorityAudio = -16;
+  static const int threadPriorityBackground = 10;
+  static const int threadPriorityDefault = 0;
+  static const int threadPriorityDisplay = -6;
+  switch (priority) {
+    case kThreadPriority_RealtimeAudio:
+      return threadPriorityAudio;
+    case kThreadPriority_Background:
+      return threadPriorityBackground;
+    case kThreadPriority_Normal:
+      return threadPriorityDefault;
+    case kThreadPriority_Display:
+      return threadPriorityDisplay;
+    default:
+      NOTREACHED() << "Unknown priority.";
+      return 0;
+  }
+}
+} // namespace
+
+//static
+void PlatformThread::SetThreadPriority(PlatformThreadHandle handle,
+                                       ThreadPriority priority) {
+  // On Android, we set the Audio priority through JNI as Audio priority
+  // will also allow the process to run while it is backgrounded.
+  if (priority == kThreadPriority_RealtimeAudio) {
+    JNIEnv* env = base::android::AttachCurrentThread();
+    Java_ThreadUtils_setThreadPriorityAudio(env, PlatformThread::CurrentId());
+    return;
+  }
+
+  // setpriority(2) will set a thread's priority if it is passed a tid as
+  // the 'process identifier', not affecting the rest of the threads in the
+  // process. Setting this priority will only succeed if the user has been
+  // granted permission to adjust nice values on the system.
+  DCHECK_NE(handle.id_, kInvalidThreadId);
+  int kNiceSetting = ThreadNiceValue(priority);
+  if (setpriority(PRIO_PROCESS, handle.id_, kNiceSetting))
+    LOG(ERROR) << "Failed to set nice value of thread to " << kNiceSetting;
+}
+
+void PlatformThread::SetName(const char* name) {
+  ThreadIdNameManager::GetInstance()->SetName(CurrentId(), name);
+  tracked_objects::ThreadData::InitializeThreadContext(name);
+}
+
+
+void InitThreading() {
+}
+
+void InitOnThread() {
+  // Threads on linux/android may inherit their priority from the thread
+  // where they were created. This sets all new threads to the default.
+  PlatformThread::SetThreadPriority(PlatformThread::CurrentHandle(),
+                                    kThreadPriority_Normal);
+}
+
+void TerminateOnThread() {
+  base::android::DetachFromVM();
+}
+
+size_t GetDefaultThreadStackSize(const pthread_attr_t& attributes) {
+  return 0;
+}
+
+bool RegisterThreadUtils(JNIEnv* env) {
+  return RegisterNativesImpl(env);
+}
+
+}  // namespace base
diff --git a/chromium/base/threading/platform_thread_linux.cc b/chromium/base/threading/platform_thread_linux.cc
new file mode 100644
index 00000000000..80227c32079
--- /dev/null
+++ b/chromium/base/threading/platform_thread_linux.cc
@@ -0,0 +1,116 @@
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "base/threading/platform_thread.h"
+
+#include <errno.h>
+#include <sched.h>
+
+#include "base/lazy_instance.h"
+#include "base/logging.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/safe_strerror_posix.h"
+#include "base/threading/thread_id_name_manager.h"
+#include "base/threading/thread_restrictions.h"
+#include "base/tracked_objects.h"
+
+#if !defined(OS_NACL)
+#include <sys/prctl.h>
+#include <sys/resource.h>
+#include <sys/syscall.h>
+#include <sys/time.h>
+#include <unistd.h>
+#endif
+
+namespace base {
+
+namespace {
+int ThreadNiceValue(ThreadPriority priority) {
+  static const int threadPriorityAudio = -10;
+  static const int threadPriorityBackground = 10;
+  static const int threadPriorityDefault = 0;
+  static const int threadPriorityDisplay = -6;
+  switch (priority) {
+    case kThreadPriority_RealtimeAudio:
+      return threadPriorityAudio;
+    case kThreadPriority_Background:
+      return threadPriorityBackground;
+    case kThreadPriority_Normal:
+      return threadPriorityDefault;
+    case kThreadPriority_Display:
+      return threadPriorityDisplay;
+    default:
+      NOTREACHED() << "Unknown priority.";
+      return 0;
+  }
+}
+} // namespace
+
+// static
+void PlatformThread::SetName(const char* name) {
+  ThreadIdNameManager::GetInstance()->SetName(CurrentId(), name);
+  tracked_objects::ThreadData::InitializeThreadContext(name);
+
+#ifndef OS_NACL
+  // On linux we can get the thread names to show up in the debugger by setting
+  // the process name for the LWP.  We don't want to do this for the main
+  // thread because that would rename the process, causing tools like killall
+  // to stop working.
+  if (PlatformThread::CurrentId() == getpid())
+    return;
+
+  // http://0pointer.de/blog/projects/name-your-threads.html
+  // Set the name for the LWP (which gets truncated to 15 characters).
+  // Note that glibc also has a 'pthread_setname_np' api, but it may not be
+  // available everywhere and it's only benefit over using prctl directly is
+  // that it can set the name of threads other than the current thread.
+  int err = prctl(PR_SET_NAME, name);
+  // We expect EPERM failures in sandboxed processes, just ignore those.
+  if (err < 0 && errno != EPERM)
+    DPLOG(ERROR) << "prctl(PR_SET_NAME)";
+#endif
+}
+
+// static
+void PlatformThread::SetThreadPriority(PlatformThreadHandle handle,
+                                       ThreadPriority priority) {
+#if !defined(OS_NACL)
+  if (priority == kThreadPriority_RealtimeAudio) {
+    const int kRealTimePrio = 8;
+
+    struct sched_param sched_param;
+    memset(&sched_param, 0, sizeof(sched_param));
+    sched_param.sched_priority = kRealTimePrio;
+
+    if (pthread_setschedparam(pthread_self(), SCHED_RR, &sched_param) == 0) {
+      // Got real time priority, no need to set nice level.
+      return;
+    }
+  }
+
+  // setpriority(2) will set a thread's priority if it is passed a tid as
+  // the 'process identifier', not affecting the rest of the threads in the
+  // process. Setting this priority will only succeed if the user has been
+  // granted permission to adjust nice values on the system.
+  DCHECK_NE(handle.id_, kInvalidThreadId);
+  int kNiceSetting = ThreadNiceValue(priority);
+  if (setpriority(PRIO_PROCESS, handle.id_, kNiceSetting))
+    LOG(ERROR) << "Failed to set nice value of thread to " << kNiceSetting;
+#endif  // !OS_NACL
+}
+
+void InitThreading() {
+}
+
+void InitOnThread() {
+}
+
+void TerminateOnThread() {
+}
+
+size_t GetDefaultThreadStackSize(const pthread_attr_t& attributes) {
+  return 0;
+}
+
+}  // namespace base
diff --git a/chromium/base/threading/platform_thread_mac.mm b/chromium/base/threading/platform_thread_mac.mm
new file mode 100644
index 00000000000..d81a286cb2c
--- /dev/null
+++ b/chromium/base/threading/platform_thread_mac.mm
@@ -0,0 +1,224 @@
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "base/threading/platform_thread.h"
+
+#import <Foundation/Foundation.h>
+#include <algorithm>
+#include <dlfcn.h>
+#include <mach/mach.h>
+#include <mach/mach_time.h>
+#include <mach/thread_policy.h>
+#include <sys/resource.h>
+
+#include "base/lazy_instance.h"
+#include "base/logging.h"
+#include "base/threading/thread_id_name_manager.h"
+#include "base/tracked_objects.h"
+
+namespace base {
+
+// If Cocoa is to be used on more than one thread, it must know that the
+// application is multithreaded.  Since it's possible to enter Cocoa code
+// from threads created by pthread_thread_create, Cocoa won't necessarily
+// be aware that the application is multithreaded.  Spawning an NSThread is
+// enough to get Cocoa to set up for multithreaded operation, so this is done
+// if necessary before pthread_thread_create spawns any threads.
+//
+// http://developer.apple.com/documentation/Cocoa/Conceptual/Multithreading/CreatingThreads/chapter_4_section_4.html
+void InitThreading() {
+  static BOOL multithreaded = [NSThread isMultiThreaded];
+  if (!multithreaded) {
+    // +[NSObject class] is idempotent.
+    [NSThread detachNewThreadSelector:@selector(class)
+                             toTarget:[NSObject class]
+                           withObject:nil];
+    multithreaded = YES;
+
+    DCHECK([NSThread isMultiThreaded]);
+  }
+}
+
+// static
+void PlatformThread::SetName(const char* name) {
+  ThreadIdNameManager::GetInstance()->SetName(CurrentId(), name);
+  tracked_objects::ThreadData::InitializeThreadContext(name);
+
+  // pthread_setname_np is only available in 10.6 or later, so test
+  // for it at runtime.
+  int (*dynamic_pthread_setname_np)(const char*);
+  *reinterpret_cast<void**>(&dynamic_pthread_setname_np) =
+      dlsym(RTLD_DEFAULT, "pthread_setname_np");
+  if (!dynamic_pthread_setname_np)
+    return;
+
+  // Mac OS X does not expose the length limit of the name, so
+  // hardcode it.
+  const int kMaxNameLength = 63;
+  std::string shortened_name = std::string(name).substr(0, kMaxNameLength);
+  // pthread_setname() fails (harmlessly) in the sandbox, ignore when it does.
+  // See http://crbug.com/47058
+  dynamic_pthread_setname_np(shortened_name.c_str());
+}
+
+namespace {
+
+void SetPriorityNormal(mach_port_t mach_thread_id) {
+  // Make thread standard policy.
+  // Please note that this call could fail in rare cases depending
+  // on runtime conditions.
+  thread_standard_policy policy;
+  kern_return_t result = thread_policy_set(mach_thread_id,
+                                           THREAD_STANDARD_POLICY,
+                                           (thread_policy_t)&policy,
+                                           THREAD_STANDARD_POLICY_COUNT);
+
+  if (result != KERN_SUCCESS)
+    DVLOG(1) << "thread_policy_set() failure: " << result;
+}
+
+// Enables time-contraint policy and priority suitable for low-latency,
+// glitch-resistant audio.
+void SetPriorityRealtimeAudio(mach_port_t mach_thread_id) {
+  kern_return_t result;
+
+  // Increase thread priority to real-time.
+
+  // Please note that the thread_policy_set() calls may fail in
+  // rare cases if the kernel decides the system is under heavy load
+  // and is unable to handle boosting the thread priority.
+  // In these cases we just return early and go on with life.
+
+  // Make thread fixed priority.
+  thread_extended_policy_data_t policy;
+  policy.timeshare = 0;  // Set to 1 for a non-fixed thread.
+  result = thread_policy_set(mach_thread_id,
+                             THREAD_EXTENDED_POLICY,
+                             (thread_policy_t)&policy,
+                             THREAD_EXTENDED_POLICY_COUNT);
+  if (result != KERN_SUCCESS) {
+    DVLOG(1) << "thread_policy_set() failure: " << result;
+    return;
+  }
+
+  // Set to relatively high priority.
+  thread_precedence_policy_data_t precedence;
+  precedence.importance = 63;
+  result = thread_policy_set(mach_thread_id,
+                             THREAD_PRECEDENCE_POLICY,
+                             (thread_policy_t)&precedence,
+                             THREAD_PRECEDENCE_POLICY_COUNT);
+  if (result != KERN_SUCCESS) {
+    DVLOG(1) << "thread_policy_set() failure: " << result;
+    return;
+  }
+
+  // Most important, set real-time constraints.
+
+  // Define the guaranteed and max fraction of time for the audio thread.
+  // These "duty cycle" values can range from 0 to 1.  A value of 0.5
+  // means the scheduler would give half the time to the thread.
+  // These values have empirically been found to yield good behavior.
+  // Good means that audio performance is high and other threads won't starve.
+  const double kGuaranteedAudioDutyCycle = 0.75;
+  const double kMaxAudioDutyCycle = 0.85;
+
+  // Define constants determining how much time the audio thread can
+  // use in a given time quantum.  All times are in milliseconds.
+
+  // About 128 frames @44.1KHz
+  const double kTimeQuantum = 2.9;
+
+  // Time guaranteed each quantum.
+  const double kAudioTimeNeeded = kGuaranteedAudioDutyCycle * kTimeQuantum;
+
+  // Maximum time each quantum.
+  const double kMaxTimeAllowed = kMaxAudioDutyCycle * kTimeQuantum;
+
+  // Get the conversion factor from milliseconds to absolute time
+  // which is what the time-constraints call needs.
+  mach_timebase_info_data_t tb_info;
+  mach_timebase_info(&tb_info);
+  double ms_to_abs_time =
+      ((double)tb_info.denom / (double)tb_info.numer) * 1000000;
+
+  thread_time_constraint_policy_data_t time_constraints;
+  time_constraints.period = kTimeQuantum * ms_to_abs_time;
+  time_constraints.computation = kAudioTimeNeeded * ms_to_abs_time;
+  time_constraints.constraint = kMaxTimeAllowed * ms_to_abs_time;
+  time_constraints.preemptible = 0;
+
+  result = thread_policy_set(mach_thread_id,
+                             THREAD_TIME_CONSTRAINT_POLICY,
+                             (thread_policy_t)&time_constraints,
+                             THREAD_TIME_CONSTRAINT_POLICY_COUNT);
+  if (result != KERN_SUCCESS)
+    DVLOG(1) << "thread_policy_set() failure: " << result;
+
+  return;
+}
+
+}  // anonymous namespace
+
+// static
+void PlatformThread::SetThreadPriority(PlatformThreadHandle handle,
+                                       ThreadPriority priority) {
+  // Convert from pthread_t to mach thread identifier.
+  mach_port_t mach_thread_id = pthread_mach_thread_np(handle.handle_);
+
+  switch (priority) {
+    case kThreadPriority_Normal:
+      SetPriorityNormal(mach_thread_id);
+      break;
+    case kThreadPriority_RealtimeAudio:
+      SetPriorityRealtimeAudio(mach_thread_id);
+      break;
+    default:
+      NOTREACHED() << "Unknown priority.";
+      break;
+  }
+}
+
+size_t GetDefaultThreadStackSize(const pthread_attr_t& attributes) {
+#if defined(OS_IOS)
+  return 0;
+#else
+  // The Mac OS X default for a pthread stack size is 512kB.
+  // Libc-594.1.4/pthreads/pthread.c's pthread_attr_init uses
+  // DEFAULT_STACK_SIZE for this purpose.
+  //
+  // 512kB isn't quite generous enough for some deeply recursive threads that
+  // otherwise request the default stack size by specifying 0. Here, adopt
+  // glibc's behavior as on Linux, which is to use the current stack size
+  // limit (ulimit -s) as the default stack size. See
+  // glibc-2.11.1/nptl/nptl-init.c's __pthread_initialize_minimal_internal. To
+  // avoid setting the limit below the Mac OS X default or the minimum usable
+  // stack size, these values are also considered. If any of these values
+  // can't be determined, or if stack size is unlimited (ulimit -s unlimited),
+  // stack_size is left at 0 to get the system default.
+  //
+  // Mac OS X normally only applies ulimit -s to the main thread stack. On
+  // contemporary OS X and Linux systems alike, this value is generally 8MB
+  // or in that neighborhood.
+  size_t default_stack_size = 0;
+  struct rlimit stack_rlimit;
+  if (pthread_attr_getstacksize(&attributes, &default_stack_size) == 0 &&
+      getrlimit(RLIMIT_STACK, &stack_rlimit) == 0 &&
+      stack_rlimit.rlim_cur != RLIM_INFINITY) {
+    default_stack_size =
+        std::max(std::max(default_stack_size,
+                          static_cast<size_t>(PTHREAD_STACK_MIN)),
+                 static_cast<size_t>(stack_rlimit.rlim_cur));
+  }
+  return default_stack_size;
+#endif
+}
+
+void InitOnThread() {
+}
+
+void TerminateOnThread() {
+}
+
+}  // namespace base
diff --git a/chromium/base/threading/platform_thread_posix.cc b/chromium/base/threading/platform_thread_posix.cc
new file mode 100644
index 00000000000..43a42eca98a
--- /dev/null
+++ b/chromium/base/threading/platform_thread_posix.cc
@@ -0,0 +1,231 @@
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "base/threading/platform_thread.h"
+
+#include <errno.h>
+#include <sched.h>
+
+#include "base/lazy_instance.h"
+#include "base/logging.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/safe_strerror_posix.h"
+#include "base/synchronization/waitable_event.h"
+#include "base/threading/thread_id_name_manager.h"
+#include "base/threading/thread_restrictions.h"
+#include "base/tracked_objects.h"
+
+#if defined(OS_MACOSX)
+#include <sys/resource.h>
+#include <algorithm>
+#endif
+
+#if defined(OS_LINUX)
+#include <sys/prctl.h>
+#include <sys/resource.h>
+#include <sys/syscall.h>
+#include <sys/time.h>
+#include <unistd.h>
+#endif
+
+namespace base {
+
+void InitThreading();
+void InitOnThread();
+void TerminateOnThread();
+size_t GetDefaultThreadStackSize(const pthread_attr_t& attributes);
+
+namespace {
+
+struct ThreadParams {
+  ThreadParams()
+      : delegate(NULL),
+        joinable(false),
+        priority(kThreadPriority_Normal),
+        handle(NULL),
+        handle_set(false, false) {
+  }
+
+  PlatformThread::Delegate* delegate;
+  bool joinable;
+  ThreadPriority priority;
+  PlatformThreadHandle* handle;
+  WaitableEvent handle_set;
+};
+
+void* ThreadFunc(void* params) {
+  base::InitOnThread();
+  ThreadParams* thread_params = static_cast<ThreadParams*>(params);
+
+  PlatformThread::Delegate* delegate = thread_params->delegate;
+  if (!thread_params->joinable)
+    base::ThreadRestrictions::SetSingletonAllowed(false);
+
+  if (thread_params->priority != kThreadPriority_Normal) {
+    PlatformThread::SetThreadPriority(PlatformThread::CurrentHandle(),
+                                      thread_params->priority);
+  }
+
+  // Stash the id in the handle so the calling thread has a complete
+  // handle, and unblock the parent thread.
+  *(thread_params->handle) = PlatformThreadHandle(pthread_self(),
+                                                  PlatformThread::CurrentId());
+  thread_params->handle_set.Signal();
+
+  ThreadIdNameManager::GetInstance()->RegisterThread(
+      PlatformThread::CurrentHandle().platform_handle(),
+      PlatformThread::CurrentId());
+
+  delegate->ThreadMain();
+
+  ThreadIdNameManager::GetInstance()->RemoveName(
+      PlatformThread::CurrentHandle().platform_handle(),
+      PlatformThread::CurrentId());
+
+  base::TerminateOnThread();
+  return NULL;
+}
+
+bool CreateThread(size_t stack_size, bool joinable,
+                  PlatformThread::Delegate* delegate,
+                  PlatformThreadHandle* thread_handle,
+                  ThreadPriority priority) {
+  base::InitThreading();
+
+  bool success = false;
+  pthread_attr_t attributes;
+  pthread_attr_init(&attributes);
+
+  // Pthreads are joinable by default, so only specify the detached
+  // attribute if the thread should be non-joinable.
+  if (!joinable) {
+    pthread_attr_setdetachstate(&attributes, PTHREAD_CREATE_DETACHED);
+  }
+
+  // Get a better default if available.
+  if (stack_size == 0)
+    stack_size = base::GetDefaultThreadStackSize(attributes);
+
+  if (stack_size > 0)
+    pthread_attr_setstacksize(&attributes, stack_size);
+
+  ThreadParams params;
+  params.delegate = delegate;
+  params.joinable = joinable;
+  params.priority = priority;
+  params.handle = thread_handle;
+
+  pthread_t handle = 0;
+  int err = pthread_create(&handle,
+                           &attributes,
+                           ThreadFunc,
+                           &params);
+  success = !err;
+  if (!success) {
+    errno = err;
+    PLOG(ERROR) << "pthread_create";
+  }
+
+  pthread_attr_destroy(&attributes);
+
+  // Don't let this call complete until the thread id
+  // is set in the handle.
+  if (success)
+    params.handle_set.Wait();
+  CHECK_EQ(handle, thread_handle->platform_handle());
+
+  return success;
+}
+
+}  // namespace
+
+// static
+PlatformThreadId PlatformThread::CurrentId() {
+  // Pthreads doesn't have the concept of a thread ID, so we have to reach down
+  // into the kernel.
+#if defined(OS_MACOSX)
+  return pthread_mach_thread_np(pthread_self());
+#elif defined(OS_LINUX)
+  return syscall(__NR_gettid);
+#elif defined(OS_ANDROID)
+  return gettid();
+#elif defined(OS_SOLARIS)
+  return pthread_self();
+#elif defined(OS_NACL) && defined(__GLIBC__)
+  return pthread_self();
+#elif defined(OS_NACL) && !defined(__GLIBC__)
+  // Pointers are 32-bits in NaCl.
+  return reinterpret_cast<int32>(pthread_self());
+#elif defined(OS_POSIX)
+  return reinterpret_cast<int64>(pthread_self());
+#endif
+}
+
+//static
+PlatformThreadHandle PlatformThread::CurrentHandle() {
+  return PlatformThreadHandle(pthread_self(), CurrentId());
+}
+
+// static
+void PlatformThread::YieldCurrentThread() {
+  sched_yield();
+}
+
+// static
+void PlatformThread::Sleep(TimeDelta duration) {
+  struct timespec sleep_time, remaining;
+
+  // Break the duration into seconds and nanoseconds.
+  // NOTE: TimeDelta's microseconds are int64s while timespec's
+  // nanoseconds are longs, so this unpacking must prevent overflow.
+  sleep_time.tv_sec = duration.InSeconds();
+  duration -= TimeDelta::FromSeconds(sleep_time.tv_sec);
+  sleep_time.tv_nsec = duration.InMicroseconds() * 1000;  // nanoseconds
+
+  while (nanosleep(&sleep_time, &remaining) == -1 && errno == EINTR)
+    sleep_time = remaining;
+}
+
+// static
+const char* PlatformThread::GetName() {
+  return ThreadIdNameManager::GetInstance()->GetName(CurrentId());
+}
+
+// static
+bool PlatformThread::Create(size_t stack_size, Delegate* delegate,
+                            PlatformThreadHandle* thread_handle) {
+  base::ThreadRestrictions::ScopedAllowWait allow_wait;
+  return CreateThread(stack_size, true /* joinable thread */,
+                      delegate, thread_handle, kThreadPriority_Normal);
+}
+
+// static
+bool PlatformThread::CreateWithPriority(size_t stack_size, Delegate* delegate,
+                                        PlatformThreadHandle* thread_handle,
+                                        ThreadPriority priority) {
+  base::ThreadRestrictions::ScopedAllowWait allow_wait;
+  return CreateThread(stack_size, true,  // joinable thread
+                      delegate, thread_handle, priority);
+}
+
+// static
+bool PlatformThread::CreateNonJoinable(size_t stack_size, Delegate* delegate) {
+  PlatformThreadHandle unused;
+
+  base::ThreadRestrictions::ScopedAllowWait allow_wait;
+  bool result = CreateThread(stack_size, false /* non-joinable thread */,
+                             delegate, &unused, kThreadPriority_Normal);
+  return result;
+}
+
+// static
+void PlatformThread::Join(PlatformThreadHandle thread_handle) {
+  // Joining another thread may block the current thread for a long time, since
+  // the thread referred to by |thread_handle| may still be running long-lived /
+  // blocking tasks.
+  base::ThreadRestrictions::AssertIOAllowed();
+  pthread_join(thread_handle.handle_, NULL);
+}
+
+}  // namespace base
diff --git a/chromium/base/threading/platform_thread_unittest.cc b/chromium/base/threading/platform_thread_unittest.cc
new file mode 100644
index 00000000000..59f29dadc3f
--- /dev/null
+++ b/chromium/base/threading/platform_thread_unittest.cc
@@ -0,0 +1,121 @@
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "base/compiler_specific.h"
+#include "base/threading/platform_thread.h"
+
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace base {
+
+// Trivial tests that thread runs and doesn't crash on create and join ---------
+
+class TrivialThread : public PlatformThread::Delegate {
+ public:
+  TrivialThread() : did_run_(false) {}
+
+  virtual void ThreadMain() OVERRIDE {
+    did_run_ = true;
+  }
+
+  bool did_run() const { return did_run_; }
+
+ private:
+  bool did_run_;
+
+  DISALLOW_COPY_AND_ASSIGN(TrivialThread);
+};
+
+TEST(PlatformThreadTest, Trivial) {
+  TrivialThread thread;
+  PlatformThreadHandle handle;
+
+  ASSERT_FALSE(thread.did_run());
+  ASSERT_TRUE(PlatformThread::Create(0, &thread, &handle));
+  PlatformThread::Join(handle);
+  ASSERT_TRUE(thread.did_run());
+}
+
+TEST(PlatformThreadTest, TrivialTimesTen) {
+  TrivialThread thread[10];
+  PlatformThreadHandle handle[arraysize(thread)];
+
+  for (size_t n = 0; n < arraysize(thread); n++)
+    ASSERT_FALSE(thread[n].did_run());
+  for (size_t n = 0; n < arraysize(thread); n++)
+    ASSERT_TRUE(PlatformThread::Create(0, &thread[n], &handle[n]));
+  for (size_t n = 0; n < arraysize(thread); n++)
+    PlatformThread::Join(handle[n]);
+  for (size_t n = 0; n < arraysize(thread); n++)
+    ASSERT_TRUE(thread[n].did_run());
+}
+
+// Tests of basic thread functions ---------------------------------------------
+
+class FunctionTestThread : public TrivialThread {
+ public:
+  FunctionTestThread() : thread_id_(0) {}
+
+  virtual void ThreadMain() OVERRIDE {
+    thread_id_ = PlatformThread::CurrentId();
+    PlatformThread::YieldCurrentThread();
+    PlatformThread::Sleep(TimeDelta::FromMilliseconds(50));
+
+    // Make sure that the thread ID is the same across calls.
+    EXPECT_EQ(thread_id_, PlatformThread::CurrentId());
+
+    TrivialThread::ThreadMain();
+  }
+
+  PlatformThreadId thread_id() const { return thread_id_; }
+
+ private:
+  PlatformThreadId thread_id_;
+
+  DISALLOW_COPY_AND_ASSIGN(FunctionTestThread);
+};
+
+TEST(PlatformThreadTest, Function) {
+  PlatformThreadId main_thread_id = PlatformThread::CurrentId();
+
+  FunctionTestThread thread;
+  PlatformThreadHandle handle;
+
+  ASSERT_FALSE(thread.did_run());
+  ASSERT_TRUE(PlatformThread::Create(0, &thread, &handle));
+  PlatformThread::Join(handle);
+  ASSERT_TRUE(thread.did_run());
+  EXPECT_NE(thread.thread_id(), main_thread_id);
+
+  // Make sure that the thread ID is the same across calls.
+  EXPECT_EQ(main_thread_id, PlatformThread::CurrentId());
+}
+
+TEST(PlatformThreadTest, FunctionTimesTen) {
+  PlatformThreadId main_thread_id = PlatformThread::CurrentId();
+
+  FunctionTestThread thread[10];
+  PlatformThreadHandle handle[arraysize(thread)];
+
+  for (size_t n = 0; n < arraysize(thread); n++)
+    ASSERT_FALSE(thread[n].did_run());
+  for (size_t n = 0; n < arraysize(thread); n++)
+    ASSERT_TRUE(PlatformThread::Create(0, &thread[n], &handle[n]));
+  for (size_t n = 0; n < arraysize(thread); n++)
+    PlatformThread::Join(handle[n]);
+  for (size_t n = 0; n < arraysize(thread); n++) {
+    ASSERT_TRUE(thread[n].did_run());
+    EXPECT_NE(thread[n].thread_id(), main_thread_id);
+
+    // Make sure no two threads get the same ID.
+    for (size_t i = 0; i < n; ++i) {
+      EXPECT_NE(thread[i].thread_id(), thread[n].thread_id());
+    }
+  }
+
+  // Make sure that the thread ID is the same across calls.
+  EXPECT_EQ(main_thread_id, PlatformThread::CurrentId());
+}
+
+}  // namespace base
diff --git a/chromium/base/threading/platform_thread_win.cc b/chromium/base/threading/platform_thread_win.cc
new file mode 100644
index 00000000000..cf1e0f60ea1
--- /dev/null
+++ b/chromium/base/threading/platform_thread_win.cc
@@ -0,0 +1,234 @@
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "base/threading/platform_thread.h"
+
+#include "base/debug/alias.h"
+#include "base/debug/profiler.h"
+#include "base/logging.h"
+#include "base/threading/thread_id_name_manager.h"
+#include "base/threading/thread_restrictions.h"
+#include "base/tracked_objects.h"
+
+#include "base/win/windows_version.h"
+
+namespace base {
+
+namespace {
+
+// The information on how to set the thread name comes from
+// a MSDN article: http://msdn2.microsoft.com/en-us/library/xcb2z8hs.aspx
+const DWORD kVCThreadNameException = 0x406D1388;
+
+typedef struct tagTHREADNAME_INFO {
+  DWORD dwType;  // Must be 0x1000.
+  LPCSTR szName;  // Pointer to name (in user addr space).
+  DWORD dwThreadID;  // Thread ID (-1=caller thread).
+  DWORD dwFlags;  // Reserved for future use, must be zero.
+} THREADNAME_INFO;
+
+// This function has try handling, so it is separated out of its caller.
+void SetNameInternal(PlatformThreadId thread_id, const char* name) {
+  THREADNAME_INFO info;
+  info.dwType = 0x1000;
+  info.szName = name;
+  info.dwThreadID = thread_id;
+  info.dwFlags = 0;
+
+  __try {
+    RaiseException(kVCThreadNameException, 0, sizeof(info)/sizeof(DWORD),
+                   reinterpret_cast<DWORD_PTR*>(&info));
+  } __except(EXCEPTION_CONTINUE_EXECUTION) {
+  }
+}
+
+struct ThreadParams {
+  PlatformThread::Delegate* delegate;
+  bool joinable;
+};
+
+DWORD __stdcall ThreadFunc(void* params) {
+  ThreadParams* thread_params = static_cast<ThreadParams*>(params);
+  PlatformThread::Delegate* delegate = thread_params->delegate;
+  if (!thread_params->joinable)
+    base::ThreadRestrictions::SetSingletonAllowed(false);
+
+  /* Retrieve a copy of the thread handle to use as the key in the
+   * thread name mapping. */
+  PlatformThreadHandle::Handle platform_handle;
+  DuplicateHandle(
+      GetCurrentProcess(),
+      GetCurrentThread(),
+      GetCurrentProcess(),
+      &platform_handle,
+      0,
+      FALSE,
+      DUPLICATE_SAME_ACCESS);
+
+  ThreadIdNameManager::GetInstance()->RegisterThread(
+      platform_handle,
+      PlatformThread::CurrentId());
+
+  delete thread_params;
+  delegate->ThreadMain();
+
+  ThreadIdNameManager::GetInstance()->RemoveName(
+      platform_handle,
+      PlatformThread::CurrentId());
+  return NULL;
+}
+
+// CreateThreadInternal() matches PlatformThread::Create(), except that
+// |out_thread_handle| may be NULL, in which case a non-joinable thread is
+// created.
+bool CreateThreadInternal(size_t stack_size,
+                          PlatformThread::Delegate* delegate,
+                          PlatformThreadHandle* out_thread_handle) {
+  unsigned int flags = 0;
+  if (stack_size > 0 && base::win::GetVersion() >= base::win::VERSION_XP) {
+    flags = STACK_SIZE_PARAM_IS_A_RESERVATION;
+  } else {
+    stack_size = 0;
+  }
+
+  ThreadParams* params = new ThreadParams;
+  params->delegate = delegate;
+  params->joinable = out_thread_handle != NULL;
+
+  // Using CreateThread here vs _beginthreadex makes thread creation a bit
+  // faster and doesn't require the loader lock to be available.  Our code will
+  // have to work running on CreateThread() threads anyway, since we run code
+  // on the Windows thread pool, etc.  For some background on the difference:
+  //   http://www.microsoft.com/msj/1099/win32/win321099.aspx
+  void* thread_handle = CreateThread(
+      NULL, stack_size, ThreadFunc, params, flags, NULL);
+  if (!thread_handle) {
+    delete params;
+    return false;
+  }
+
+  if (out_thread_handle)
+    *out_thread_handle = PlatformThreadHandle(thread_handle);
+  else
+    CloseHandle(thread_handle);
+  return true;
+}
+
+}  // namespace
+
+// static
+PlatformThreadId PlatformThread::CurrentId() {
+  return GetCurrentThreadId();
+}
+
+// static
+PlatformThreadHandle PlatformThread::CurrentHandle() {
+  NOTIMPLEMENTED(); // See OpenThread()
+  return PlatformThreadHandle();
+}
+
+// static
+void PlatformThread::YieldCurrentThread() {
+  ::Sleep(0);
+}
+
+// static
+void PlatformThread::Sleep(TimeDelta duration) {
+  ::Sleep(duration.InMillisecondsRoundedUp());
+}
+
+// static
+void PlatformThread::SetName(const char* name) {
+  ThreadIdNameManager::GetInstance()->SetName(CurrentId(), name);
+
+  // On Windows only, we don't need to tell the profiler about the "BrokerEvent"
+  // thread, as it exists only in the chrome.exe image, and never spawns or runs
+  // tasks (items which could be profiled).  This test avoids the notification,
+  // which would also (as a side effect) initialize the profiler in this unused
+  // context, including setting up thread local storage, etc.  The performance
+  // impact is not terrible, but there is no reason to do initialize it.
+  if (0 != strcmp(name, "BrokerEvent"))
+    tracked_objects::ThreadData::InitializeThreadContext(name);
+
+  // The debugger needs to be around to catch the name in the exception.  If
+  // there isn't a debugger, we are just needlessly throwing an exception.
+  // If this image file is instrumented, we raise the exception anyway
+  // to provide the profiler with human-readable thread names.
+  if (!::IsDebuggerPresent() && !base::debug::IsBinaryInstrumented())
+    return;
+
+  SetNameInternal(CurrentId(), name);
+}
+
+// static
+const char* PlatformThread::GetName() {
+  return ThreadIdNameManager::GetInstance()->GetName(CurrentId());
+}
+
+// static
+bool PlatformThread::Create(size_t stack_size, Delegate* delegate,
+                            PlatformThreadHandle* thread_handle) {
+  DCHECK(thread_handle);
+  return CreateThreadInternal(stack_size, delegate, thread_handle);
+}
+
+// static
+bool PlatformThread::CreateWithPriority(size_t stack_size, Delegate* delegate,
+                                        PlatformThreadHandle* thread_handle,
+                                        ThreadPriority priority) {
+  bool result = Create(stack_size, delegate, thread_handle);
+  if (result)
+    SetThreadPriority(*thread_handle, priority);
+  return result;
+}
+
+// static
+bool PlatformThread::CreateNonJoinable(size_t stack_size, Delegate* delegate) {
+  return CreateThreadInternal(stack_size, delegate, NULL);
+}
+
+// static
+void PlatformThread::Join(PlatformThreadHandle thread_handle) {
+  DCHECK(thread_handle.handle_);
+  // TODO(willchan): Enable this check once I can get it to work for Windows
+  // shutdown.
+  // Joining another thread may block the current thread for a long time, since
+  // the thread referred to by |thread_handle| may still be running long-lived /
+  // blocking tasks.
+#if 0
+  base::ThreadRestrictions::AssertIOAllowed();
+#endif
+
+  // Wait for the thread to exit.  It should already have terminated but make
+  // sure this assumption is valid.
+  DWORD result = WaitForSingleObject(thread_handle.handle_, INFINITE);
+  if (result != WAIT_OBJECT_0) {
+    // Debug info for bug 127931.
+    DWORD error = GetLastError();
+    debug::Alias(&error);
+    debug::Alias(&result);
+    debug::Alias(&thread_handle.handle_);
+    CHECK(false);
+  }
+
+  CloseHandle(thread_handle.handle_);
+}
+
+// static
+void PlatformThread::SetThreadPriority(PlatformThreadHandle handle,
+                                       ThreadPriority priority) {
+  switch (priority) {
+    case kThreadPriority_Normal:
+      ::SetThreadPriority(handle.handle_, THREAD_PRIORITY_NORMAL);
+      break;
+    case kThreadPriority_RealtimeAudio:
+      ::SetThreadPriority(handle.handle_, THREAD_PRIORITY_TIME_CRITICAL);
+      break;
+    default:
+      NOTREACHED() << "Unknown priority.";
+      break;
+  }
+}
+
+}  // namespace base
diff --git a/chromium/base/threading/post_task_and_reply_impl.cc b/chromium/base/threading/post_task_and_reply_impl.cc
new file mode 100644
index 00000000000..f464c6acad2
--- /dev/null
+++ b/chromium/base/threading/post_task_and_reply_impl.cc
@@ -0,0 +1,90 @@
+// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "base/threading/post_task_and_reply_impl.h"
+
+#include "base/bind.h"
+#include "base/location.h"
+#include "base/message_loop/message_loop_proxy.h"
+
+namespace base {
+
+namespace {
+
+// This relay class remembers the MessageLoop that it was created on, and
+// ensures that both the |task| and |reply| Closures are deleted on this same
+// thread. Also, |task| is guaranteed to be deleted before |reply| is run or
+// deleted.
+//
+// If this is not possible because the originating MessageLoop is no longer
+// available, the the |task| and |reply| Closures are leaked.  Leaking is
+// considered preferable to having a thread-safetey violations caused by
+// invoking the Closure destructor on the wrong thread.
+class PostTaskAndReplyRelay {
+ public:
+  PostTaskAndReplyRelay(const tracked_objects::Location& from_here,
+                        const Closure& task, const Closure& reply)
+      : from_here_(from_here),
+        origin_loop_(MessageLoopProxy::current()) {
+    task_ = task;
+    reply_ = reply;
+  }
+
+  ~PostTaskAndReplyRelay() {
+    DCHECK(origin_loop_->BelongsToCurrentThread());
+    task_.Reset();
+    reply_.Reset();
+  }
+
+  void Run() {
+    task_.Run();
+    origin_loop_->PostTask(
+        from_here_,
+        Bind(&PostTaskAndReplyRelay::RunReplyAndSelfDestruct,
+             base::Unretained(this)));
+  }
+
+ private:
+  void RunReplyAndSelfDestruct() {
+    DCHECK(origin_loop_->BelongsToCurrentThread());
+
+    // Force |task_| to be released before |reply_| is to ensure that no one
+    // accidentally depends on |task_| keeping one of its arguments alive while
+    // |reply_| is executing.
+    task_.Reset();
+
+    reply_.Run();
+
+    // Cue mission impossible theme.
+    delete this;
+  }
+
+  tracked_objects::Location from_here_;
+  scoped_refptr<MessageLoopProxy> origin_loop_;
+  Closure reply_;
+  Closure task_;
+};
+
+}  // namespace
+
+namespace internal {
+
+bool PostTaskAndReplyImpl::PostTaskAndReply(
+    const tracked_objects::Location& from_here,
+    const Closure& task,
+    const Closure& reply) {
+  PostTaskAndReplyRelay* relay =
+      new PostTaskAndReplyRelay(from_here, task, reply);
+  if (!PostTask(from_here, Bind(&PostTaskAndReplyRelay::Run,
+                                Unretained(relay)))) {
+    delete relay;
+    return false;
+  }
+
+  return true;
+}
+
+}  // namespace internal
+
+}  // namespace base
diff --git a/chromium/base/threading/post_task_and_reply_impl.h b/chromium/base/threading/post_task_and_reply_impl.h
new file mode 100644
index 00000000000..076a46d69e8
--- /dev/null
+++ b/chromium/base/threading/post_task_and_reply_impl.h
@@ -0,0 +1,42 @@
+// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// This file contains the implementation shared by
+// MessageLoopProxy::PostTaskAndReply and WorkerPool::PostTaskAndReply.
+
+#ifndef BASE_THREADING_POST_TASK_AND_REPLY_IMPL_H_
+#define BASE_THREADING_POST_TASK_AND_REPLY_IMPL_H_
+
+#include "base/callback_forward.h"
+#include "base/location.h"
+
+namespace base {
+namespace internal {
+
+// Inherit from this in a class that implements PostTask appropriately
+// for sending to a destination thread.
+//
+// Note that 'reply' will always get posted back to your current
+// MessageLoop.
+//
+// If you're looking for a concrete implementation of
+// PostTaskAndReply, you probably want base::MessageLoopProxy, or you
+// may want base::WorkerPool.
+class PostTaskAndReplyImpl {
+ public:
+  // Implementation for MessageLoopProxy::PostTaskAndReply and
+  // WorkerPool::PostTaskAndReply.
+  bool PostTaskAndReply(const tracked_objects::Location& from_here,
+                        const Closure& task,
+                        const Closure& reply);
+
+ private:
+  virtual bool PostTask(const tracked_objects::Location& from_here,
+                        const Closure& task) = 0;
+};
+
+}  // namespace internal
+}  // namespace base
+
+#endif  // BASE_THREADING_POST_TASK_AND_REPLY_IMPL_H_
diff --git a/chromium/base/threading/sequenced_worker_pool.cc b/chromium/base/threading/sequenced_worker_pool.cc
new file mode 100644
index 00000000000..d9921689fe8
--- /dev/null
+++ b/chromium/base/threading/sequenced_worker_pool.cc
@@ -0,0 +1,1287 @@
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "base/threading/sequenced_worker_pool.h"
+
+#include <list>
+#include <map>
+#include <set>
+#include <utility>
+#include <vector>
+
+#include "base/atomic_sequence_num.h"
+#include "base/callback.h"
+#include "base/compiler_specific.h"
+#include "base/critical_closure.h"
+#include "base/debug/trace_event.h"
+#include "base/lazy_instance.h"
+#include "base/logging.h"
+#include "base/memory/linked_ptr.h"
+#include "base/message_loop/message_loop_proxy.h"
+#include "base/stl_util.h"
+#include "base/strings/stringprintf.h"
+#include "base/synchronization/condition_variable.h"
+#include "base/synchronization/lock.h"
+#include "base/threading/platform_thread.h"
+#include "base/threading/simple_thread.h"
+#include "base/threading/thread_local.h"
+#include "base/threading/thread_restrictions.h"
+#include "base/time/time.h"
+#include "base/tracked_objects.h"
+
+#if defined(OS_MACOSX)
+#include "base/mac/scoped_nsautorelease_pool.h"
+#endif
+
+#if !defined(OS_NACL)
+#include "base/metrics/histogram.h"
+#endif
+
+namespace base {
+
+namespace {
+
+struct SequencedTask : public TrackingInfo  {
+  SequencedTask()
+      : sequence_token_id(0),
+        trace_id(0),
+        sequence_task_number(0),
+        shutdown_behavior(SequencedWorkerPool::BLOCK_SHUTDOWN) {}
+
+  explicit SequencedTask(const tracked_objects::Location& from_here)
+      : base::TrackingInfo(from_here, TimeTicks()),
+        sequence_token_id(0),
+        trace_id(0),
+        sequence_task_number(0),
+        shutdown_behavior(SequencedWorkerPool::BLOCK_SHUTDOWN) {}
+
+  ~SequencedTask() {}
+
+  int sequence_token_id;
+  int trace_id;
+  int64 sequence_task_number;
+  SequencedWorkerPool::WorkerShutdown shutdown_behavior;
+  tracked_objects::Location posted_from;
+  Closure task;
+
+  // Non-delayed tasks and delayed tasks are managed together by time-to-run
+  // order. We calculate the time by adding the posted time and the given delay.
+  TimeTicks time_to_run;
+};
+
+struct SequencedTaskLessThan {
+ public:
+  bool operator()(const SequencedTask& lhs, const SequencedTask& rhs) const {
+    if (lhs.time_to_run < rhs.time_to_run)
+      return true;
+
+    if (lhs.time_to_run > rhs.time_to_run)
+      return false;
+
+    // If the time happen to match, then we use the sequence number to decide.
+    return lhs.sequence_task_number < rhs.sequence_task_number;
+  }
+};
+
+// SequencedWorkerPoolTaskRunner ---------------------------------------------
+// A TaskRunner which posts tasks to a SequencedWorkerPool with a
+// fixed ShutdownBehavior.
+//
+// Note that this class is RefCountedThreadSafe (inherited from TaskRunner).
+class SequencedWorkerPoolTaskRunner : public TaskRunner {
+ public:
+  SequencedWorkerPoolTaskRunner(
+      const scoped_refptr<SequencedWorkerPool>& pool,
+      SequencedWorkerPool::WorkerShutdown shutdown_behavior);
+
+  // TaskRunner implementation
+  virtual bool PostDelayedTask(const tracked_objects::Location& from_here,
+                               const Closure& task,
+                               TimeDelta delay) OVERRIDE;
+  virtual bool RunsTasksOnCurrentThread() const OVERRIDE;
+
+ private:
+  virtual ~SequencedWorkerPoolTaskRunner();
+
+  const scoped_refptr<SequencedWorkerPool> pool_;
+
+  const SequencedWorkerPool::WorkerShutdown shutdown_behavior_;
+
+  DISALLOW_COPY_AND_ASSIGN(SequencedWorkerPoolTaskRunner);
+};
+
+SequencedWorkerPoolTaskRunner::SequencedWorkerPoolTaskRunner(
+    const scoped_refptr<SequencedWorkerPool>& pool,
+    SequencedWorkerPool::WorkerShutdown shutdown_behavior)
+    : pool_(pool),
+      shutdown_behavior_(shutdown_behavior) {
+}
+
+SequencedWorkerPoolTaskRunner::~SequencedWorkerPoolTaskRunner() {
+}
+
+bool SequencedWorkerPoolTaskRunner::PostDelayedTask(
+    const tracked_objects::Location& from_here,
+    const Closure& task,
+    TimeDelta delay) {
+  if (delay == TimeDelta()) {
+    return pool_->PostWorkerTaskWithShutdownBehavior(
+        from_here, task, shutdown_behavior_);
+  }
+  return pool_->PostDelayedWorkerTask(from_here, task, delay);
+}
+
+bool SequencedWorkerPoolTaskRunner::RunsTasksOnCurrentThread() const {
+  return pool_->RunsTasksOnCurrentThread();
+}
+
+// SequencedWorkerPoolSequencedTaskRunner ------------------------------------
+// A SequencedTaskRunner which posts tasks to a SequencedWorkerPool with a
+// fixed sequence token.
+//
+// Note that this class is RefCountedThreadSafe (inherited from TaskRunner).
+class SequencedWorkerPoolSequencedTaskRunner : public SequencedTaskRunner {
+ public:
+  SequencedWorkerPoolSequencedTaskRunner(
+      const scoped_refptr<SequencedWorkerPool>& pool,
+      SequencedWorkerPool::SequenceToken token,
+      SequencedWorkerPool::WorkerShutdown shutdown_behavior);
+
+  // TaskRunner implementation
+  virtual bool PostDelayedTask(const tracked_objects::Location& from_here,
+                               const Closure& task,
+                               TimeDelta delay) OVERRIDE;
+  virtual bool RunsTasksOnCurrentThread() const OVERRIDE;
+
+  // SequencedTaskRunner implementation
+  virtual bool PostNonNestableDelayedTask(
+      const tracked_objects::Location& from_here,
+      const Closure& task,
+      TimeDelta delay) OVERRIDE;
+
+ private:
+  virtual ~SequencedWorkerPoolSequencedTaskRunner();
+
+  const scoped_refptr<SequencedWorkerPool> pool_;
+
+  const SequencedWorkerPool::SequenceToken token_;
+
+  const SequencedWorkerPool::WorkerShutdown shutdown_behavior_;
+
+  DISALLOW_COPY_AND_ASSIGN(SequencedWorkerPoolSequencedTaskRunner);
+};
+
+SequencedWorkerPoolSequencedTaskRunner::SequencedWorkerPoolSequencedTaskRunner(
+    const scoped_refptr<SequencedWorkerPool>& pool,
+    SequencedWorkerPool::SequenceToken token,
+    SequencedWorkerPool::WorkerShutdown shutdown_behavior)
+    : pool_(pool),
+      token_(token),
+      shutdown_behavior_(shutdown_behavior) {
+}
+
+SequencedWorkerPoolSequencedTaskRunner::
+~SequencedWorkerPoolSequencedTaskRunner() {
+}
+
+bool SequencedWorkerPoolSequencedTaskRunner::PostDelayedTask(
+    const tracked_objects::Location& from_here,
+    const Closure& task,
+    TimeDelta delay) {
+  if (delay == TimeDelta()) {
+    return pool_->PostSequencedWorkerTaskWithShutdownBehavior(
+        token_, from_here, task, shutdown_behavior_);
+  }
+  return pool_->PostDelayedSequencedWorkerTask(token_, from_here, task, delay);
+}
+
+bool SequencedWorkerPoolSequencedTaskRunner::RunsTasksOnCurrentThread() const {
+  return pool_->IsRunningSequenceOnCurrentThread(token_);
+}
+
+bool SequencedWorkerPoolSequencedTaskRunner::PostNonNestableDelayedTask(
+    const tracked_objects::Location& from_here,
+    const Closure& task,
+    TimeDelta delay) {
+  // There's no way to run nested tasks, so simply forward to
+  // PostDelayedTask.
+  return PostDelayedTask(from_here, task, delay);
+}
+
+// Create a process-wide unique ID to represent this task in trace events. This
+// will be mangled with a Process ID hash to reduce the likelyhood of colliding
+// with MessageLoop pointers on other processes.
+uint64 GetTaskTraceID(const SequencedTask& task,
+                      void* pool) {
+  return (static_cast<uint64>(task.trace_id) << 32) |
+         static_cast<uint64>(reinterpret_cast<intptr_t>(pool));
+}
+
+base::LazyInstance<base::ThreadLocalPointer<
+    SequencedWorkerPool::SequenceToken> > g_lazy_tls_ptr =
+        LAZY_INSTANCE_INITIALIZER;
+
+}  // namespace
+
+// Worker ---------------------------------------------------------------------
+
+class SequencedWorkerPool::Worker : public SimpleThread {
+ public:
+  // Hold a (cyclic) ref to |worker_pool|, since we want to keep it
+  // around as long as we are running.
+  Worker(const scoped_refptr<SequencedWorkerPool>& worker_pool,
+         int thread_number,
+         const std::string& thread_name_prefix);
+  virtual ~Worker();
+
+  // SimpleThread implementation. This actually runs the background thread.
+  virtual void Run() OVERRIDE;
+
+  void set_running_task_info(SequenceToken token,
+                             WorkerShutdown shutdown_behavior) {
+    running_sequence_ = token;
+    running_shutdown_behavior_ = shutdown_behavior;
+  }
+
+  SequenceToken running_sequence() const {
+    return running_sequence_;
+  }
+
+  WorkerShutdown running_shutdown_behavior() const {
+    return running_shutdown_behavior_;
+  }
+
+ private:
+  scoped_refptr<SequencedWorkerPool> worker_pool_;
+  SequenceToken running_sequence_;
+  WorkerShutdown running_shutdown_behavior_;
+
+  DISALLOW_COPY_AND_ASSIGN(Worker);
+};
+
+// Inner ----------------------------------------------------------------------
+
+class SequencedWorkerPool::Inner {
+ public:
+  // Take a raw pointer to |worker| to avoid cycles (since we're owned
+  // by it).
+  Inner(SequencedWorkerPool* worker_pool, size_t max_threads,
+        const std::string& thread_name_prefix,
+        TestingObserver* observer);
+
+  ~Inner();
+
+  SequenceToken GetSequenceToken();
+
+  SequenceToken GetNamedSequenceToken(const std::string& name);
+
+  // This function accepts a name and an ID. If the name is null, the
+  // token ID is used. This allows us to implement the optional name lookup
+  // from a single function without having to enter the lock a separate time.
+  bool PostTask(const std::string* optional_token_name,
+                SequenceToken sequence_token,
+                WorkerShutdown shutdown_behavior,
+                const tracked_objects::Location& from_here,
+                const Closure& task,
+                TimeDelta delay);
+
+  bool RunsTasksOnCurrentThread() const;
+
+  bool IsRunningSequenceOnCurrentThread(SequenceToken sequence_token) const;
+
+  void CleanupForTesting();
+
+  void SignalHasWorkForTesting();
+
+  int GetWorkSignalCountForTesting() const;
+
+  void Shutdown(int max_blocking_tasks_after_shutdown);
+
+  bool IsShutdownInProgress();
+
+  // Runs the worker loop on the background thread.
+  void ThreadLoop(Worker* this_worker);
+
+ private:
+  enum GetWorkStatus {
+    GET_WORK_FOUND,
+    GET_WORK_NOT_FOUND,
+    GET_WORK_WAIT,
+  };
+
+  enum CleanupState {
+    CLEANUP_REQUESTED,
+    CLEANUP_STARTING,
+    CLEANUP_RUNNING,
+    CLEANUP_FINISHING,
+    CLEANUP_DONE,
+  };
+
+  // Called from within the lock, this converts the given token name into a
+  // token ID, creating a new one if necessary.
+  int LockedGetNamedTokenID(const std::string& name);
+
+  // Called from within the lock, this returns the next sequence task number.
+  int64 LockedGetNextSequenceTaskNumber();
+
+  // Called from within the lock, returns the shutdown behavior of the task
+  // running on the currently executing worker thread. If invoked from a thread
+  // that is not one of the workers, returns CONTINUE_ON_SHUTDOWN.
+  WorkerShutdown LockedCurrentThreadShutdownBehavior() const;
+
+  // Gets new task. There are 3 cases depending on the return value:
+  //
+  // 1) If the return value is |GET_WORK_FOUND|, |task| is filled in and should
+  //    be run immediately.
+  // 2) If the return value is |GET_WORK_NOT_FOUND|, there are no tasks to run,
+  //    and |task| is not filled in. In this case, the caller should wait until
+  //    a task is posted.
+  // 3) If the return value is |GET_WORK_WAIT|, there are no tasks to run
+  //    immediately, and |task| is not filled in. Likewise, |wait_time| is
+  //    filled in the time to wait until the next task to run. In this case, the
+  //    caller should wait the time.
+  //
+  // In any case, the calling code should clear the given
+  // delete_these_outside_lock vector the next time the lock is released.
+  // See the implementation for a more detailed description.
+  GetWorkStatus GetWork(SequencedTask* task,
+                        TimeDelta* wait_time,
+                        std::vector<Closure>* delete_these_outside_lock);
+
+  void HandleCleanup();
+
+  // Peforms init and cleanup around running the given task. WillRun...
+  // returns the value from PrepareToStartAdditionalThreadIfNecessary.
+  // The calling code should call FinishStartingAdditionalThread once the
+  // lock is released if the return values is nonzero.
+  int WillRunWorkerTask(const SequencedTask& task);
+  void DidRunWorkerTask(const SequencedTask& task);
+
+  // Returns true if there are no threads currently running the given
+  // sequence token.
+  bool IsSequenceTokenRunnable(int sequence_token_id) const;
+
+  // Checks if all threads are busy and the addition of one more could run an
+  // additional task waiting in the queue. This must be called from within
+  // the lock.
+  //
+  // If another thread is helpful, this will mark the thread as being in the
+  // process of starting and returns the index of the new thread which will be
+  // 0 or more. The caller should then call FinishStartingAdditionalThread to
+  // complete initialization once the lock is released.
+  //
+  // If another thread is not necessary, returne 0;
+  //
+  // See the implementedion for more.
+  int PrepareToStartAdditionalThreadIfHelpful();
+
+  // The second part of thread creation after
+  // PrepareToStartAdditionalThreadIfHelpful with the thread number it
+  // generated. This actually creates the thread and should be called outside
+  // the lock to avoid blocking important work starting a thread in the lock.
+  void FinishStartingAdditionalThread(int thread_number);
+
+  // Signal |has_work_| and increment |has_work_signal_count_|.
+  void SignalHasWork();
+
+  // Checks whether there is work left that's blocking shutdown. Must be
+  // called inside the lock.
+  bool CanShutdown() const;
+
+  SequencedWorkerPool* const worker_pool_;
+
+  // The last sequence number used. Managed by GetSequenceToken, since this
+  // only does threadsafe increment operations, you do not need to hold the
+  // lock. This is class-static to make SequenceTokens issued by
+  // GetSequenceToken unique across SequencedWorkerPool instances.
+  static base::StaticAtomicSequenceNumber g_last_sequence_number_;
+
+  // This lock protects |everything in this class|. Do not read or modify
+  // anything without holding this lock. Do not block while holding this
+  // lock.
+  mutable Lock lock_;
+
+  // Condition variable that is waited on by worker threads until new
+  // tasks are posted or shutdown starts.
+  ConditionVariable has_work_cv_;
+
+  // Condition variable that is waited on by non-worker threads (in
+  // Shutdown()) until CanShutdown() goes to true.
+  ConditionVariable can_shutdown_cv_;
+
+  // The maximum number of worker threads we'll create.
+  const size_t max_threads_;
+
+  const std::string thread_name_prefix_;
+
+  // Associates all known sequence token names with their IDs.
+  std::map<std::string, int> named_sequence_tokens_;
+
+  // Owning pointers to all threads we've created so far, indexed by
+  // ID. Since we lazily create threads, this may be less than
+  // max_threads_ and will be initially empty.
+  typedef std::map<PlatformThreadId, linked_ptr<Worker> > ThreadMap;
+  ThreadMap threads_;
+
+  // Set to true when we're in the process of creating another thread.
+  // See PrepareToStartAdditionalThreadIfHelpful for more.
+  bool thread_being_created_;
+
+  // Number of threads currently waiting for work.
+  size_t waiting_thread_count_;
+
+  // Number of threads currently running tasks that have the BLOCK_SHUTDOWN
+  // or SKIP_ON_SHUTDOWN flag set.
+  size_t blocking_shutdown_thread_count_;
+
+  // A set of all pending tasks in time-to-run order. These are tasks that are
+  // either waiting for a thread to run on, waiting for their time to run,
+  // or blocked on a previous task in their sequence. We have to iterate over
+  // the tasks by time-to-run order, so we use the set instead of the
+  // traditional priority_queue.
+  typedef std::set<SequencedTask, SequencedTaskLessThan> PendingTaskSet;
+  PendingTaskSet pending_tasks_;
+
+  // The next sequence number for a new sequenced task.
+  int64 next_sequence_task_number_;
+
+  // Number of tasks in the pending_tasks_ list that are marked as blocking
+  // shutdown.
+  size_t blocking_shutdown_pending_task_count_;
+
+  // Lists all sequence tokens currently executing.
+  std::set<int> current_sequences_;
+
+  // An ID for each posted task to distinguish the task from others in traces.
+  int trace_id_;
+
+  // Set when Shutdown is called and no further tasks should be
+  // allowed, though we may still be running existing tasks.
+  bool shutdown_called_;
+
+  // The number of new BLOCK_SHUTDOWN tasks that may be posted after Shudown()
+  // has been called.
+  int max_blocking_tasks_after_shutdown_;
+
+  // State used to cleanup for testing, all guarded by lock_.
+  CleanupState cleanup_state_;
+  size_t cleanup_idlers_;
+  ConditionVariable cleanup_cv_;
+
+  TestingObserver* const testing_observer_;
+
+  DISALLOW_COPY_AND_ASSIGN(Inner);
+};
+
+// Worker definitions ---------------------------------------------------------
+
+SequencedWorkerPool::Worker::Worker(
+    const scoped_refptr<SequencedWorkerPool>& worker_pool,
+    int thread_number,
+    const std::string& prefix)
+    : SimpleThread(
+          prefix + StringPrintf("Worker%d", thread_number).c_str()),
+      worker_pool_(worker_pool),
+      running_shutdown_behavior_(CONTINUE_ON_SHUTDOWN) {
+  Start();
+}
+
+SequencedWorkerPool::Worker::~Worker() {
+}
+
+void SequencedWorkerPool::Worker::Run() {
+  // Store a pointer to the running sequence in thread local storage for
+  // static function access.
+  g_lazy_tls_ptr.Get().Set(&running_sequence_);
+
+  // Just jump back to the Inner object to run the thread, since it has all the
+  // tracking information and queues. It might be more natural to implement
+  // using DelegateSimpleThread and have Inner implement the Delegate to avoid
+  // having these worker objects at all, but that method lacks the ability to
+  // send thread-specific information easily to the thread loop.
+  worker_pool_->inner_->ThreadLoop(this);
+  // Release our cyclic reference once we're done.
+  worker_pool_ = NULL;
+}
+
+// Inner definitions ---------------------------------------------------------
+
+SequencedWorkerPool::Inner::Inner(
+    SequencedWorkerPool* worker_pool,
+    size_t max_threads,
+    const std::string& thread_name_prefix,
+    TestingObserver* observer)
+    : worker_pool_(worker_pool),
+      lock_(),
+      has_work_cv_(&lock_),
+      can_shutdown_cv_(&lock_),
+      max_threads_(max_threads),
+      thread_name_prefix_(thread_name_prefix),
+      thread_being_created_(false),
+      waiting_thread_count_(0),
+      blocking_shutdown_thread_count_(0),
+      next_sequence_task_number_(0),
+      blocking_shutdown_pending_task_count_(0),
+      trace_id_(0),
+      shutdown_called_(false),
+      max_blocking_tasks_after_shutdown_(0),
+      cleanup_state_(CLEANUP_DONE),
+      cleanup_idlers_(0),
+      cleanup_cv_(&lock_),
+      testing_observer_(observer) {}
+
+SequencedWorkerPool::Inner::~Inner() {
+  // You must call Shutdown() before destroying the pool.
+  DCHECK(shutdown_called_);
+
+  // Need to explicitly join with the threads before they're destroyed or else
+  // they will be running when our object is half torn down.
+  for (ThreadMap::iterator it = threads_.begin(); it != threads_.end(); ++it)
+    it->second->Join();
+  threads_.clear();
+
+  if (testing_observer_)
+    testing_observer_->OnDestruct();
+}
+
+SequencedWorkerPool::SequenceToken
+SequencedWorkerPool::Inner::GetSequenceToken() {
+  // Need to add one because StaticAtomicSequenceNumber starts at zero, which
+  // is used as a sentinel value in SequenceTokens.
+  return SequenceToken(g_last_sequence_number_.GetNext() + 1);
+}
+
+SequencedWorkerPool::SequenceToken
+SequencedWorkerPool::Inner::GetNamedSequenceToken(const std::string& name) {
+  AutoLock lock(lock_);
+  return SequenceToken(LockedGetNamedTokenID(name));
+}
+
+bool SequencedWorkerPool::Inner::PostTask(
+    const std::string* optional_token_name,
+    SequenceToken sequence_token,
+    WorkerShutdown shutdown_behavior,
+    const tracked_objects::Location& from_here,
+    const Closure& task,
+    TimeDelta delay) {
+  DCHECK(delay == TimeDelta() || shutdown_behavior == SKIP_ON_SHUTDOWN);
+  SequencedTask sequenced(from_here);
+  sequenced.sequence_token_id = sequence_token.id_;
+  sequenced.shutdown_behavior = shutdown_behavior;
+  sequenced.posted_from = from_here;
+  sequenced.task =
+      shutdown_behavior == BLOCK_SHUTDOWN ?
+      base::MakeCriticalClosure(task) : task;
+  sequenced.time_to_run = TimeTicks::Now() + delay;
+
+  int create_thread_id = 0;
+  {
+    AutoLock lock(lock_);
+    if (shutdown_called_) {
+      if (shutdown_behavior != BLOCK_SHUTDOWN ||
+          LockedCurrentThreadShutdownBehavior() == CONTINUE_ON_SHUTDOWN) {
+        return false;
+      }
+      if (max_blocking_tasks_after_shutdown_ <= 0) {
+        DLOG(WARNING) << "BLOCK_SHUTDOWN task disallowed";
+        return false;
+      }
+      max_blocking_tasks_after_shutdown_ -= 1;
+    }
+
+    // The trace_id is used for identifying the task in about:tracing.
+    sequenced.trace_id = trace_id_++;
+
+    TRACE_EVENT_FLOW_BEGIN0("task", "SequencedWorkerPool::PostTask",
+        TRACE_ID_MANGLE(GetTaskTraceID(sequenced, static_cast<void*>(this))));
+
+    sequenced.sequence_task_number = LockedGetNextSequenceTaskNumber();
+
+    // Now that we have the lock, apply the named token rules.
+    if (optional_token_name)
+      sequenced.sequence_token_id = LockedGetNamedTokenID(*optional_token_name);
+
+    pending_tasks_.insert(sequenced);
+    if (shutdown_behavior == BLOCK_SHUTDOWN)
+      blocking_shutdown_pending_task_count_++;
+
+    create_thread_id = PrepareToStartAdditionalThreadIfHelpful();
+  }
+
+  // Actually start the additional thread or signal an existing one now that
+  // we're outside the lock.
+  if (create_thread_id)
+    FinishStartingAdditionalThread(create_thread_id);
+  else
+    SignalHasWork();
+
+  return true;
+}
+
+bool SequencedWorkerPool::Inner::RunsTasksOnCurrentThread() const {
+  AutoLock lock(lock_);
+  return ContainsKey(threads_, PlatformThread::CurrentId());
+}
+
+bool SequencedWorkerPool::Inner::IsRunningSequenceOnCurrentThread(
+    SequenceToken sequence_token) const {
+  AutoLock lock(lock_);
+  ThreadMap::const_iterator found = threads_.find(PlatformThread::CurrentId());
+  if (found == threads_.end())
+    return false;
+  return sequence_token.Equals(found->second->running_sequence());
+}
+
+// See https://code.google.com/p/chromium/issues/detail?id=168415
+void SequencedWorkerPool::Inner::CleanupForTesting() {
+  DCHECK(!RunsTasksOnCurrentThread());
+  base::ThreadRestrictions::ScopedAllowWait allow_wait;
+  AutoLock lock(lock_);
+  CHECK_EQ(CLEANUP_DONE, cleanup_state_);
+  if (shutdown_called_)
+    return;
+  if (pending_tasks_.empty() && waiting_thread_count_ == threads_.size())
+    return;
+  cleanup_state_ = CLEANUP_REQUESTED;
+  cleanup_idlers_ = 0;
+  has_work_cv_.Signal();
+  while (cleanup_state_ != CLEANUP_DONE)
+    cleanup_cv_.Wait();
+}
+
+void SequencedWorkerPool::Inner::SignalHasWorkForTesting() {
+  SignalHasWork();
+}
+
+void SequencedWorkerPool::Inner::Shutdown(
+    int max_new_blocking_tasks_after_shutdown) {
+  DCHECK_GE(max_new_blocking_tasks_after_shutdown, 0);
+  {
+    AutoLock lock(lock_);
+    // Cleanup and Shutdown should not be called concurrently.
+    CHECK_EQ(CLEANUP_DONE, cleanup_state_);
+    if (shutdown_called_)
+      return;
+    shutdown_called_ = true;
+    max_blocking_tasks_after_shutdown_ = max_new_blocking_tasks_after_shutdown;
+
+    // Tickle the threads. This will wake up a waiting one so it will know that
+    // it can exit, which in turn will wake up any other waiting ones.
+    SignalHasWork();
+
+    // There are no pending or running tasks blocking shutdown, we're done.
+    if (CanShutdown())
+      return;
+  }
+
+  // If we're here, then something is blocking shutdown.  So wait for
+  // CanShutdown() to go to true.
+
+  if (testing_observer_)
+    testing_observer_->WillWaitForShutdown();
+
+#if !defined(OS_NACL)
+  TimeTicks shutdown_wait_begin = TimeTicks::Now();
+#endif
+
+  {
+    base::ThreadRestrictions::ScopedAllowWait allow_wait;
+    AutoLock lock(lock_);
+    while (!CanShutdown())
+      can_shutdown_cv_.Wait();
+  }
+#if !defined(OS_NACL)
+  UMA_HISTOGRAM_TIMES("SequencedWorkerPool.ShutdownDelayTime",
+                      TimeTicks::Now() - shutdown_wait_begin);
+#endif
+}
+
+bool SequencedWorkerPool::Inner::IsShutdownInProgress() {
+    AutoLock lock(lock_);
+    return shutdown_called_;
+}
+
+void SequencedWorkerPool::Inner::ThreadLoop(Worker* this_worker) {
+  {
+    AutoLock lock(lock_);
+    DCHECK(thread_being_created_);
+    thread_being_created_ = false;
+    std::pair<ThreadMap::iterator, bool> result =
+        threads_.insert(
+            std::make_pair(this_worker->tid(), make_linked_ptr(this_worker)));
+    DCHECK(result.second);
+
+    while (true) {
+#if defined(OS_MACOSX)
+      base::mac::ScopedNSAutoreleasePool autorelease_pool;
+#endif
+
+      HandleCleanup();
+
+      // See GetWork for what delete_these_outside_lock is doing.
+      SequencedTask task;
+      TimeDelta wait_time;
+      std::vector<Closure> delete_these_outside_lock;
+      GetWorkStatus status =
+          GetWork(&task, &wait_time, &delete_these_outside_lock);
+      if (status == GET_WORK_FOUND) {
+        TRACE_EVENT_FLOW_END0("task", "SequencedWorkerPool::PostTask",
+            TRACE_ID_MANGLE(GetTaskTraceID(task, static_cast<void*>(this))));
+        TRACE_EVENT2("task", "SequencedWorkerPool::ThreadLoop",
+                     "src_file", task.posted_from.file_name(),
+                     "src_func", task.posted_from.function_name());
+        int new_thread_id = WillRunWorkerTask(task);
+        {
+          AutoUnlock unlock(lock_);
+          // There may be more work available, so wake up another
+          // worker thread. (Technically not required, since we
+          // already get a signal for each new task, but it doesn't
+          // hurt.)
+          SignalHasWork();
+          delete_these_outside_lock.clear();
+
+          // Complete thread creation outside the lock if necessary.
+          if (new_thread_id)
+            FinishStartingAdditionalThread(new_thread_id);
+
+          this_worker->set_running_task_info(
+              SequenceToken(task.sequence_token_id), task.shutdown_behavior);
+
+          tracked_objects::TrackedTime start_time =
+              tracked_objects::ThreadData::NowForStartOfRun(task.birth_tally);
+
+          task.task.Run();
+
+          tracked_objects::ThreadData::TallyRunOnNamedThreadIfTracking(task,
+              start_time, tracked_objects::ThreadData::NowForEndOfRun());
+
+          // Make sure our task is erased outside the lock for the
+          // same reason we do this with delete_these_oustide_lock.
+          // Also, do it before calling set_running_task_info() so
+          // that sequence-checking from within the task's destructor
+          // still works.
+          task.task = Closure();
+
+          this_worker->set_running_task_info(
+              SequenceToken(), CONTINUE_ON_SHUTDOWN);
+        }
+        DidRunWorkerTask(task);  // Must be done inside the lock.
+      } else if (cleanup_state_ == CLEANUP_RUNNING) {
+        switch (status) {
+          case GET_WORK_WAIT: {
+              AutoUnlock unlock(lock_);
+              delete_these_outside_lock.clear();
+            }
+            break;
+          case GET_WORK_NOT_FOUND:
+            CHECK(delete_these_outside_lock.empty());
+            cleanup_state_ = CLEANUP_FINISHING;
+            cleanup_cv_.Broadcast();
+            break;
+          default:
+            NOTREACHED();
+        }
+      } else {
+        // When we're terminating and there's no more work, we can
+        // shut down, other workers can complete any pending or new tasks.
+        // We can get additional tasks posted after shutdown_called_ is set
+        // but only worker threads are allowed to post tasks at that time, and
+        // the workers responsible for posting those tasks will be available
+        // to run them. Also, there may be some tasks stuck behind running
+        // ones with the same sequence token, but additional threads won't
+        // help this case.
+        if (shutdown_called_ &&
+            blocking_shutdown_pending_task_count_ == 0)
+          break;
+        waiting_thread_count_++;
+
+        switch (status) {
+          case GET_WORK_NOT_FOUND:
+            has_work_cv_.Wait();
+            break;
+          case GET_WORK_WAIT:
+            has_work_cv_.TimedWait(wait_time);
+            break;
+          default:
+            NOTREACHED();
+        }
+        waiting_thread_count_--;
+      }
+    }
+  }  // Release lock_.
+
+  // We noticed we should exit. Wake up the next worker so it knows it should
+  // exit as well (because the Shutdown() code only signals once).
+  SignalHasWork();
+
+  // Possibly unblock shutdown.
+  can_shutdown_cv_.Signal();
+}
+
+void SequencedWorkerPool::Inner::HandleCleanup() {
+  lock_.AssertAcquired();
+  if (cleanup_state_ == CLEANUP_DONE)
+    return;
+  if (cleanup_state_ == CLEANUP_REQUESTED) {
+    // We win, we get to do the cleanup as soon as the others wise up and idle.
+    cleanup_state_ = CLEANUP_STARTING;
+    while (thread_being_created_ ||
+           cleanup_idlers_ != threads_.size() - 1) {
+      has_work_cv_.Signal();
+      cleanup_cv_.Wait();
+    }
+    cleanup_state_ = CLEANUP_RUNNING;
+    return;
+  }
+  if (cleanup_state_ == CLEANUP_STARTING) {
+    // Another worker thread is cleaning up, we idle here until thats done.
+    ++cleanup_idlers_;
+    cleanup_cv_.Broadcast();
+    while (cleanup_state_ != CLEANUP_FINISHING) {
+      cleanup_cv_.Wait();
+    }
+    --cleanup_idlers_;
+    cleanup_cv_.Broadcast();
+    return;
+  }
+  if (cleanup_state_ == CLEANUP_FINISHING) {
+    // We wait for all idlers to wake up prior to being DONE.
+    while (cleanup_idlers_ != 0) {
+      cleanup_cv_.Broadcast();
+      cleanup_cv_.Wait();
+    }
+    if (cleanup_state_ == CLEANUP_FINISHING) {
+      cleanup_state_ = CLEANUP_DONE;
+      cleanup_cv_.Signal();
+    }
+    return;
+  }
+}
+
+int SequencedWorkerPool::Inner::LockedGetNamedTokenID(
+    const std::string& name) {
+  lock_.AssertAcquired();
+  DCHECK(!name.empty());
+
+  std::map<std::string, int>::const_iterator found =
+      named_sequence_tokens_.find(name);
+  if (found != named_sequence_tokens_.end())
+    return found->second;  // Got an existing one.
+
+  // Create a new one for this name.
+  SequenceToken result = GetSequenceToken();
+  named_sequence_tokens_.insert(std::make_pair(name, result.id_));
+  return result.id_;
+}
+
+int64 SequencedWorkerPool::Inner::LockedGetNextSequenceTaskNumber() {
+  lock_.AssertAcquired();
+  // We assume that we never create enough tasks to wrap around.
+  return next_sequence_task_number_++;
+}
+
+SequencedWorkerPool::WorkerShutdown
+SequencedWorkerPool::Inner::LockedCurrentThreadShutdownBehavior() const {
+  lock_.AssertAcquired();
+  ThreadMap::const_iterator found = threads_.find(PlatformThread::CurrentId());
+  if (found == threads_.end())
+    return CONTINUE_ON_SHUTDOWN;
+  return found->second->running_shutdown_behavior();
+}
+
+SequencedWorkerPool::Inner::GetWorkStatus SequencedWorkerPool::Inner::GetWork(
+    SequencedTask* task,
+    TimeDelta* wait_time,
+    std::vector<Closure>* delete_these_outside_lock) {
+  lock_.AssertAcquired();
+
+#if !defined(OS_NACL)
+  UMA_HISTOGRAM_COUNTS_100("SequencedWorkerPool.TaskCount",
+                           static_cast<int>(pending_tasks_.size()));
+#endif
+
+  // Find the next task with a sequence token that's not currently in use.
+  // If the token is in use, that means another thread is running something
+  // in that sequence, and we can't run it without going out-of-order.
+  //
+  // This algorithm is simple and fair, but inefficient in some cases. For
+  // example, say somebody schedules 1000 slow tasks with the same sequence
+  // number. We'll have to go through all those tasks each time we feel like
+  // there might be work to schedule. If this proves to be a problem, we
+  // should make this more efficient.
+  //
+  // One possible enhancement would be to keep a map from sequence ID to a
+  // list of pending but currently blocked SequencedTasks for that ID.
+  // When a worker finishes a task of one sequence token, it can pick up the
+  // next one from that token right away.
+  //
+  // This may lead to starvation if there are sufficient numbers of sequences
+  // in use. To alleviate this, we could add an incrementing priority counter
+  // to each SequencedTask. Then maintain a priority_queue of all runnable
+  // tasks, sorted by priority counter. When a sequenced task is completed
+  // we would pop the head element off of that tasks pending list and add it
+  // to the priority queue. Then we would run the first item in the priority
+  // queue.
+
+  GetWorkStatus status = GET_WORK_NOT_FOUND;
+  int unrunnable_tasks = 0;
+  PendingTaskSet::iterator i = pending_tasks_.begin();
+  // We assume that the loop below doesn't take too long and so we can just do
+  // a single call to TimeTicks::Now().
+  const TimeTicks current_time = TimeTicks::Now();
+  while (i != pending_tasks_.end()) {
+    if (!IsSequenceTokenRunnable(i->sequence_token_id)) {
+      unrunnable_tasks++;
+      ++i;
+      continue;
+    }
+
+    if (shutdown_called_ && i->shutdown_behavior != BLOCK_SHUTDOWN) {
+      // We're shutting down and the task we just found isn't blocking
+      // shutdown. Delete it and get more work.
+      //
+      // Note that we do not want to delete unrunnable tasks. Deleting a task
+      // can have side effects (like freeing some objects) and deleting a
+      // task that's supposed to run after one that's currently running could
+      // cause an obscure crash.
+      //
+      // We really want to delete these tasks outside the lock in case the
+      // closures are holding refs to objects that want to post work from
+      // their destructorss (which would deadlock). The closures are
+      // internally refcounted, so we just need to keep a copy of them alive
+      // until the lock is exited. The calling code can just clear() the
+      // vector they passed to us once the lock is exited to make this
+      // happen.
+      delete_these_outside_lock->push_back(i->task);
+      pending_tasks_.erase(i++);
+      continue;
+    }
+
+    if (i->time_to_run > current_time) {
+      // The time to run has not come yet.
+      *wait_time = i->time_to_run - current_time;
+      status = GET_WORK_WAIT;
+      if (cleanup_state_ == CLEANUP_RUNNING) {
+        // Deferred tasks are deleted when cleaning up, see Inner::ThreadLoop.
+        delete_these_outside_lock->push_back(i->task);
+        pending_tasks_.erase(i);
+      }
+      break;
+    }
+
+    // Found a runnable task.
+    *task = *i;
+    pending_tasks_.erase(i);
+    if (task->shutdown_behavior == BLOCK_SHUTDOWN) {
+      blocking_shutdown_pending_task_count_--;
+    }
+
+    status = GET_WORK_FOUND;
+    break;
+  }
+
+  // Track the number of tasks we had to skip over to see if we should be
+  // making this more efficient. If this number ever becomes large or is
+  // frequently "some", we should consider the optimization above.
+#if !defined(OS_NACL)
+  UMA_HISTOGRAM_COUNTS_100("SequencedWorkerPool.UnrunnableTaskCount",
+                           unrunnable_tasks);
+#endif
+  return status;
+}
+
+int SequencedWorkerPool::Inner::WillRunWorkerTask(const SequencedTask& task) {
+  lock_.AssertAcquired();
+
+  // Mark the task's sequence number as in use.
+  if (task.sequence_token_id)
+    current_sequences_.insert(task.sequence_token_id);
+
+  // Ensure that threads running tasks posted with either SKIP_ON_SHUTDOWN
+  // or BLOCK_SHUTDOWN will prevent shutdown until that task or thread
+  // completes.
+  if (task.shutdown_behavior != CONTINUE_ON_SHUTDOWN)
+    blocking_shutdown_thread_count_++;
+
+  // We just picked up a task. Since StartAdditionalThreadIfHelpful only
+  // creates a new thread if there is no free one, there is a race when posting
+  // tasks that many tasks could have been posted before a thread started
+  // running them, so only one thread would have been created. So we also check
+  // whether we should create more threads after removing our task from the
+  // queue, which also has the nice side effect of creating the workers from
+  // background threads rather than the main thread of the app.
+  //
+  // If another thread wasn't created, we want to wake up an existing thread
+  // if there is one waiting to pick up the next task.
+  //
+  // Note that we really need to do this *before* running the task, not
+  // after. Otherwise, if more than one task is posted, the creation of the
+  // second thread (since we only create one at a time) will be blocked by
+  // the execution of the first task, which could be arbitrarily long.
+  return PrepareToStartAdditionalThreadIfHelpful();
+}
+
+void SequencedWorkerPool::Inner::DidRunWorkerTask(const SequencedTask& task) {
+  lock_.AssertAcquired();
+
+  if (task.shutdown_behavior != CONTINUE_ON_SHUTDOWN) {
+    DCHECK_GT(blocking_shutdown_thread_count_, 0u);
+    blocking_shutdown_thread_count_--;
+  }
+
+  if (task.sequence_token_id)
+    current_sequences_.erase(task.sequence_token_id);
+}
+
+bool SequencedWorkerPool::Inner::IsSequenceTokenRunnable(
+    int sequence_token_id) const {
+  lock_.AssertAcquired();
+  return !sequence_token_id ||
+      current_sequences_.find(sequence_token_id) ==
+          current_sequences_.end();
+}
+
+int SequencedWorkerPool::Inner::PrepareToStartAdditionalThreadIfHelpful() {
+  lock_.AssertAcquired();
+  // How thread creation works:
+  //
+  // We'de like to avoid creating threads with the lock held. However, we
+  // need to be sure that we have an accurate accounting of the threads for
+  // proper Joining and deltion on shutdown.
+  //
+  // We need to figure out if we need another thread with the lock held, which
+  // is what this function does. It then marks us as in the process of creating
+  // a thread. When we do shutdown, we wait until the thread_being_created_
+  // flag is cleared, which ensures that the new thread is properly added to
+  // all the data structures and we can't leak it. Once shutdown starts, we'll
+  // refuse to create more threads or they would be leaked.
+  //
+  // Note that this creates a mostly benign race condition on shutdown that
+  // will cause fewer workers to be created than one would expect. It isn't
+  // much of an issue in real life, but affects some tests. Since we only spawn
+  // one worker at a time, the following sequence of events can happen:
+  //
+  //  1. Main thread posts a bunch of unrelated tasks that would normally be
+  //     run on separate threads.
+  //  2. The first task post causes us to start a worker. Other tasks do not
+  //     cause a worker to start since one is pending.
+  //  3. Main thread initiates shutdown.
+  //  4. No more threads are created since the shutdown_called_ flag is set.
+  //
+  // The result is that one may expect that max_threads_ workers to be created
+  // given the workload, but in reality fewer may be created because the
+  // sequence of thread creation on the background threads is racing with the
+  // shutdown call.
+  if (!shutdown_called_ &&
+      !thread_being_created_ &&
+      cleanup_state_ == CLEANUP_DONE &&
+      threads_.size() < max_threads_ &&
+      waiting_thread_count_ == 0) {
+    // We could use an additional thread if there's work to be done.
+    for (PendingTaskSet::const_iterator i = pending_tasks_.begin();
+         i != pending_tasks_.end(); ++i) {
+      if (IsSequenceTokenRunnable(i->sequence_token_id)) {
+        // Found a runnable task, mark the thread as being started.
+        thread_being_created_ = true;
+        return static_cast<int>(threads_.size() + 1);
+      }
+    }
+  }
+  return 0;
+}
+
+void SequencedWorkerPool::Inner::FinishStartingAdditionalThread(
+    int thread_number) {
+  // Called outside of the lock.
+  DCHECK(thread_number > 0);
+
+  // The worker is assigned to the list when the thread actually starts, which
+  // will manage the memory of the pointer.
+  new Worker(worker_pool_, thread_number, thread_name_prefix_);
+}
+
+void SequencedWorkerPool::Inner::SignalHasWork() {
+  has_work_cv_.Signal();
+  if (testing_observer_) {
+    testing_observer_->OnHasWork();
+  }
+}
+
+bool SequencedWorkerPool::Inner::CanShutdown() const {
+  lock_.AssertAcquired();
+  // See PrepareToStartAdditionalThreadIfHelpful for how thread creation works.
+  return !thread_being_created_ &&
+         blocking_shutdown_thread_count_ == 0 &&
+         blocking_shutdown_pending_task_count_ == 0;
+}
+
+base::StaticAtomicSequenceNumber
+SequencedWorkerPool::Inner::g_last_sequence_number_;
+
+// SequencedWorkerPool --------------------------------------------------------
+
+// static
+SequencedWorkerPool::SequenceToken
+SequencedWorkerPool::GetSequenceTokenForCurrentThread() {
+  // Don't construct lazy instance on check.
+  if (g_lazy_tls_ptr == NULL)
+    return SequenceToken();
+
+  SequencedWorkerPool::SequenceToken* token = g_lazy_tls_ptr.Get().Get();
+  if (!token)
+    return SequenceToken();
+  return *token;
+}
+
+SequencedWorkerPool::SequencedWorkerPool(
+    size_t max_threads,
+    const std::string& thread_name_prefix)
+    : constructor_message_loop_(MessageLoopProxy::current()),
+      inner_(new Inner(this, max_threads, thread_name_prefix, NULL)) {
+}
+
+SequencedWorkerPool::SequencedWorkerPool(
+    size_t max_threads,
+    const std::string& thread_name_prefix,
+    TestingObserver* observer)
+    : constructor_message_loop_(MessageLoopProxy::current()),
+      inner_(new Inner(this, max_threads, thread_name_prefix, observer)) {
+}
+
+SequencedWorkerPool::~SequencedWorkerPool() {}
+
+void SequencedWorkerPool::OnDestruct() const {
+  DCHECK(constructor_message_loop_.get());
+  // Avoid deleting ourselves on a worker thread (which would
+  // deadlock).
+  if (RunsTasksOnCurrentThread()) {
+    constructor_message_loop_->DeleteSoon(FROM_HERE, this);
+  } else {
+    delete this;
+  }
+}
+
+SequencedWorkerPool::SequenceToken SequencedWorkerPool::GetSequenceToken() {
+  return inner_->GetSequenceToken();
+}
+
+SequencedWorkerPool::SequenceToken SequencedWorkerPool::GetNamedSequenceToken(
+    const std::string& name) {
+  return inner_->GetNamedSequenceToken(name);
+}
+
+scoped_refptr<SequencedTaskRunner> SequencedWorkerPool::GetSequencedTaskRunner(
+    SequenceToken token) {
+  return GetSequencedTaskRunnerWithShutdownBehavior(token, BLOCK_SHUTDOWN);
+}
+
+scoped_refptr<SequencedTaskRunner>
+SequencedWorkerPool::GetSequencedTaskRunnerWithShutdownBehavior(
+    SequenceToken token, WorkerShutdown shutdown_behavior) {
+  return new SequencedWorkerPoolSequencedTaskRunner(
+      this, token, shutdown_behavior);
+}
+
+scoped_refptr<TaskRunner>
+SequencedWorkerPool::GetTaskRunnerWithShutdownBehavior(
+    WorkerShutdown shutdown_behavior) {
+  return new SequencedWorkerPoolTaskRunner(this, shutdown_behavior);
+}
+
+bool SequencedWorkerPool::PostWorkerTask(
+    const tracked_objects::Location& from_here,
+    const Closure& task) {
+  return inner_->PostTask(NULL, SequenceToken(), BLOCK_SHUTDOWN,
+                          from_here, task, TimeDelta());
+}
+
+bool SequencedWorkerPool::PostDelayedWorkerTask(
+    const tracked_objects::Location& from_here,
+    const Closure& task,
+    TimeDelta delay) {
+  WorkerShutdown shutdown_behavior =
+      delay == TimeDelta() ? BLOCK_SHUTDOWN : SKIP_ON_SHUTDOWN;
+  return inner_->PostTask(NULL, SequenceToken(), shutdown_behavior,
+                          from_here, task, delay);
+}
+
+bool SequencedWorkerPool::PostWorkerTaskWithShutdownBehavior(
+    const tracked_objects::Location& from_here,
+    const Closure& task,
+    WorkerShutdown shutdown_behavior) {
+  return inner_->PostTask(NULL, SequenceToken(), shutdown_behavior,
+                          from_here, task, TimeDelta());
+}
+
+bool SequencedWorkerPool::PostSequencedWorkerTask(
+    SequenceToken sequence_token,
+    const tracked_objects::Location& from_here,
+    const Closure& task) {
+  return inner_->PostTask(NULL, sequence_token, BLOCK_SHUTDOWN,
+                          from_here, task, TimeDelta());
+}
+
+bool SequencedWorkerPool::PostDelayedSequencedWorkerTask(
+    SequenceToken sequence_token,
+    const tracked_objects::Location& from_here,
+    const Closure& task,
+    TimeDelta delay) {
+  WorkerShutdown shutdown_behavior =
+      delay == TimeDelta() ? BLOCK_SHUTDOWN : SKIP_ON_SHUTDOWN;
+  return inner_->PostTask(NULL, sequence_token, shutdown_behavior,
+                          from_here, task, delay);
+}
+
+bool SequencedWorkerPool::PostNamedSequencedWorkerTask(
+    const std::string& token_name,
+    const tracked_objects::Location& from_here,
+    const Closure& task) {
+  DCHECK(!token_name.empty());
+  return inner_->PostTask(&token_name, SequenceToken(), BLOCK_SHUTDOWN,
+                          from_here, task, TimeDelta());
+}
+
+bool SequencedWorkerPool::PostSequencedWorkerTaskWithShutdownBehavior(
+    SequenceToken sequence_token,
+    const tracked_objects::Location& from_here,
+    const Closure& task,
+    WorkerShutdown shutdown_behavior) {
+  return inner_->PostTask(NULL, sequence_token, shutdown_behavior,
+                          from_here, task, TimeDelta());
+}
+
+bool SequencedWorkerPool::PostDelayedTask(
+    const tracked_objects::Location& from_here,
+    const Closure& task,
+    TimeDelta delay) {
+  return PostDelayedWorkerTask(from_here, task, delay);
+}
+
+bool SequencedWorkerPool::RunsTasksOnCurrentThread() const {
+  return inner_->RunsTasksOnCurrentThread();
+}
+
+bool SequencedWorkerPool::IsRunningSequenceOnCurrentThread(
+    SequenceToken sequence_token) const {
+  return inner_->IsRunningSequenceOnCurrentThread(sequence_token);
+}
+
+void SequencedWorkerPool::FlushForTesting() {
+  inner_->CleanupForTesting();
+}
+
+void SequencedWorkerPool::SignalHasWorkForTesting() {
+  inner_->SignalHasWorkForTesting();
+}
+
+void SequencedWorkerPool::Shutdown(int max_new_blocking_tasks_after_shutdown) {
+  DCHECK(constructor_message_loop_->BelongsToCurrentThread());
+  inner_->Shutdown(max_new_blocking_tasks_after_shutdown);
+}
+
+bool SequencedWorkerPool::IsShutdownInProgress() {
+  return inner_->IsShutdownInProgress();
+}
+
+}  // namespace base
diff --git a/chromium/base/threading/sequenced_worker_pool.h b/chromium/base/threading/sequenced_worker_pool.h
new file mode 100644
index 00000000000..1bd275b206d
--- /dev/null
+++ b/chromium/base/threading/sequenced_worker_pool.h
@@ -0,0 +1,358 @@
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef BASE_THREADING_SEQUENCED_WORKER_POOL_H_
+#define BASE_THREADING_SEQUENCED_WORKER_POOL_H_
+
+#include <cstddef>
+#include <string>
+
+#include "base/base_export.h"
+#include "base/basictypes.h"
+#include "base/callback_forward.h"
+#include "base/memory/ref_counted.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/task_runner.h"
+
+namespace tracked_objects {
+class Location;
+}  // namespace tracked_objects
+
+namespace base {
+
+class MessageLoopProxy;
+
+template <class T> class DeleteHelper;
+
+class SequencedTaskRunner;
+
+// A worker thread pool that enforces ordering between sets of tasks. It also
+// allows you to specify what should happen to your tasks on shutdown.
+//
+// To enforce ordering, get a unique sequence token from the pool and post all
+// tasks you want to order with the token. All tasks with the same token are
+// guaranteed to execute serially, though not necessarily on the same thread.
+// This means that:
+//
+//   - No two tasks with the same token will run at the same time.
+//
+//   - Given two tasks T1 and T2 with the same token such that T2 will
+//     run after T1, then T2 will start after T1 is destroyed.
+//
+//   - If T2 will run after T1, then all memory changes in T1 and T1's
+//     destruction will be visible to T2.
+//
+// Example:
+//   SequencedWorkerPool::SequenceToken token = pool.GetSequenceToken();
+//   pool.PostSequencedWorkerTask(token, SequencedWorkerPool::SKIP_ON_SHUTDOWN,
+//                                FROM_HERE, base::Bind(...));
+//   pool.PostSequencedWorkerTask(token, SequencedWorkerPool::SKIP_ON_SHUTDOWN,
+//                                FROM_HERE, base::Bind(...));
+//
+// You can make named sequence tokens to make it easier to share a token
+// across different components.
+//
+// You can also post tasks to the pool without ordering using PostWorkerTask.
+// These will be executed in an unspecified order. The order of execution
+// between tasks with different sequence tokens is also unspecified.
+//
+// This class may be leaked on shutdown to facilitate fast shutdown. The
+// expected usage, however, is to call Shutdown(), which correctly accounts
+// for CONTINUE_ON_SHUTDOWN behavior and is required for BLOCK_SHUTDOWN
+// behavior.
+//
+// Implementation note: This does not use a base::WorkerPool since that does
+// not enforce shutdown semantics or allow us to specify how many worker
+// threads to run. For the typical use case of random background work, we don't
+// necessarily want to be super aggressive about creating threads.
+//
+// Note that SequencedWorkerPool is RefCountedThreadSafe (inherited
+// from TaskRunner).
+class BASE_EXPORT SequencedWorkerPool : public TaskRunner {
+ public:
+  // Defines what should happen to a task posted to the worker pool on
+  // shutdown.
+  enum WorkerShutdown {
+    // Tasks posted with this mode which have not run at shutdown will be
+    // deleted rather than run, and any tasks with this mode running at
+    // shutdown will be ignored (the worker thread will not be joined).
+    //
+    // This option provides a nice way to post stuff you don't want blocking
+    // shutdown. For example, you might be doing a slow DNS lookup and if it's
+    // blocked on the OS, you may not want to stop shutdown, since the result
+    // doesn't really matter at that point.
+    //
+    // However, you need to be very careful what you do in your callback when
+    // you use this option. Since the thread will continue to run until the OS
+    // terminates the process, the app can be in the process of tearing down
+    // when you're running. This means any singletons or global objects you
+    // use may suddenly become invalid out from under you. For this reason,
+    // it's best to use this only for slow but simple operations like the DNS
+    // example.
+    CONTINUE_ON_SHUTDOWN,
+
+    // Tasks posted with this mode that have not started executing at
+    // shutdown will be deleted rather than executed. However, any tasks that
+    // have already begun executing when shutdown is called will be allowed
+    // to continue, and will block shutdown until completion.
+    //
+    // Note: Because Shutdown() may block while these tasks are executing,
+    // care must be taken to ensure that they do not block on the thread that
+    // called Shutdown(), as this may lead to deadlock.
+    SKIP_ON_SHUTDOWN,
+
+    // Tasks posted with this mode will block shutdown until they're
+    // executed. Since this can have significant performance implications,
+    // use sparingly.
+    //
+    // Generally, this should be used only for user data, for example, a task
+    // writing a preference file.
+    //
+    // If a task is posted during shutdown, it will not get run since the
+    // workers may already be stopped. In this case, the post operation will
+    // fail (return false) and the task will be deleted.
+    BLOCK_SHUTDOWN,
+  };
+
+  // Opaque identifier that defines sequencing of tasks posted to the worker
+  // pool.
+  class SequenceToken {
+   public:
+    SequenceToken() : id_(0) {}
+    ~SequenceToken() {}
+
+    bool Equals(const SequenceToken& other) const {
+      return id_ == other.id_;
+    }
+
+    // Returns false if current thread is executing an unsequenced task.
+    bool IsValid() const {
+      return id_ != 0;
+    }
+
+   private:
+    friend class SequencedWorkerPool;
+
+    explicit SequenceToken(int id) : id_(id) {}
+
+    int id_;
+  };
+
+  // Allows tests to perform certain actions.
+  class TestingObserver {
+   public:
+    virtual ~TestingObserver() {}
+    virtual void OnHasWork() = 0;
+    virtual void WillWaitForShutdown() = 0;
+    virtual void OnDestruct() = 0;
+  };
+
+  // Gets the SequencedToken of the current thread.
+  // If current thread is not a SequencedWorkerPool worker thread or is running
+  // an unsequenced task, returns an invalid SequenceToken.
+  static SequenceToken GetSequenceTokenForCurrentThread();
+
+  // When constructing a SequencedWorkerPool, there must be a
+  // MessageLoop on the current thread unless you plan to deliberately
+  // leak it.
+
+  // Pass the maximum number of threads (they will be lazily created as needed)
+  // and a prefix for the thread name to aid in debugging.
+  SequencedWorkerPool(size_t max_threads,
+                      const std::string& thread_name_prefix);
+
+  // Like above, but with |observer| for testing.  Does not take
+  // ownership of |observer|.
+  SequencedWorkerPool(size_t max_threads,
+                      const std::string& thread_name_prefix,
+                      TestingObserver* observer);
+
+  // Returns a unique token that can be used to sequence tasks posted to
+  // PostSequencedWorkerTask(). Valid tokens are always nonzero.
+  SequenceToken GetSequenceToken();
+
+  // Returns the sequence token associated with the given name. Calling this
+  // function multiple times with the same string will always produce the
+  // same sequence token. If the name has not been used before, a new token
+  // will be created.
+  SequenceToken GetNamedSequenceToken(const std::string& name);
+
+  // Returns a SequencedTaskRunner wrapper which posts to this
+  // SequencedWorkerPool using the given sequence token. Tasks with nonzero
+  // delay are posted with SKIP_ON_SHUTDOWN behavior and tasks with zero delay
+  // are posted with BLOCK_SHUTDOWN behavior.
+  scoped_refptr<SequencedTaskRunner> GetSequencedTaskRunner(
+      SequenceToken token);
+
+  // Returns a SequencedTaskRunner wrapper which posts to this
+  // SequencedWorkerPool using the given sequence token. Tasks with nonzero
+  // delay are posted with SKIP_ON_SHUTDOWN behavior and tasks with zero delay
+  // are posted with the given shutdown behavior.
+  scoped_refptr<SequencedTaskRunner> GetSequencedTaskRunnerWithShutdownBehavior(
+      SequenceToken token,
+      WorkerShutdown shutdown_behavior);
+
+  // Returns a TaskRunner wrapper which posts to this SequencedWorkerPool using
+  // the given shutdown behavior. Tasks with nonzero delay are posted with
+  // SKIP_ON_SHUTDOWN behavior and tasks with zero delay are posted with the
+  // given shutdown behavior.
+  scoped_refptr<TaskRunner> GetTaskRunnerWithShutdownBehavior(
+      WorkerShutdown shutdown_behavior);
+
+  // Posts the given task for execution in the worker pool. Tasks posted with
+  // this function will execute in an unspecified order on a background thread.
+  // Returns true if the task was posted. If your tasks have ordering
+  // requirements, see PostSequencedWorkerTask().
+  //
+  // This class will attempt to delete tasks that aren't run
+  // (non-block-shutdown semantics) but can't guarantee that this happens. If
+  // all worker threads are busy running CONTINUE_ON_SHUTDOWN tasks, there
+  // will be no workers available to delete these tasks. And there may be
+  // tasks with the same sequence token behind those CONTINUE_ON_SHUTDOWN
+  // tasks. Deleting those tasks before the previous one has completed could
+  // cause nondeterministic crashes because the task could be keeping some
+  // objects alive which do work in their destructor, which could voilate the
+  // assumptions of the running task.
+  //
+  // The task will be guaranteed to run to completion before shutdown
+  // (BLOCK_SHUTDOWN semantics).
+  //
+  // Returns true if the task was posted successfully. This may fail during
+  // shutdown regardless of the specified ShutdownBehavior.
+  bool PostWorkerTask(const tracked_objects::Location& from_here,
+                      const Closure& task);
+
+  // Same as PostWorkerTask but allows a delay to be specified (although doing
+  // so changes the shutdown behavior). The task will be run after the given
+  // delay has elapsed.
+  //
+  // If the delay is nonzero, the task won't be guaranteed to run to completion
+  // before shutdown (SKIP_ON_SHUTDOWN semantics) to avoid shutdown hangs.
+  // If the delay is zero, this behaves exactly like PostWorkerTask, i.e. the
+  // task will be guaranteed to run to completion before shutdown
+  // (BLOCK_SHUTDOWN semantics).
+  bool PostDelayedWorkerTask(const tracked_objects::Location& from_here,
+                             const Closure& task,
+                             TimeDelta delay);
+
+  // Same as PostWorkerTask but allows specification of the shutdown behavior.
+  bool PostWorkerTaskWithShutdownBehavior(
+      const tracked_objects::Location& from_here,
+      const Closure& task,
+      WorkerShutdown shutdown_behavior);
+
+  // Like PostWorkerTask above, but provides sequencing semantics. This means
+  // that tasks posted with the same sequence token (see GetSequenceToken())
+  // are guaranteed to execute in order. This is useful in cases where you're
+  // doing operations that may depend on previous ones, like appending to a
+  // file.
+  //
+  // The task will be guaranteed to run to completion before shutdown
+  // (BLOCK_SHUTDOWN semantics).
+  //
+  // Returns true if the task was posted successfully. This may fail during
+  // shutdown regardless of the specified ShutdownBehavior.
+  bool PostSequencedWorkerTask(SequenceToken sequence_token,
+                               const tracked_objects::Location& from_here,
+                               const Closure& task);
+
+  // Like PostSequencedWorkerTask above, but allows you to specify a named
+  // token, which saves an extra call to GetNamedSequenceToken.
+  bool PostNamedSequencedWorkerTask(const std::string& token_name,
+                                    const tracked_objects::Location& from_here,
+                                    const Closure& task);
+
+  // Same as PostSequencedWorkerTask but allows a delay to be specified
+  // (although doing so changes the shutdown behavior). The task will be run
+  // after the given delay has elapsed.
+  //
+  // If the delay is nonzero, the task won't be guaranteed to run to completion
+  // before shutdown (SKIP_ON_SHUTDOWN semantics) to avoid shutdown hangs.
+  // If the delay is zero, this behaves exactly like PostSequencedWorkerTask,
+  // i.e. the task will be guaranteed to run to completion before shutdown
+  // (BLOCK_SHUTDOWN semantics).
+  bool PostDelayedSequencedWorkerTask(
+      SequenceToken sequence_token,
+      const tracked_objects::Location& from_here,
+      const Closure& task,
+      TimeDelta delay);
+
+  // Same as PostSequencedWorkerTask but allows specification of the shutdown
+  // behavior.
+  bool PostSequencedWorkerTaskWithShutdownBehavior(
+      SequenceToken sequence_token,
+      const tracked_objects::Location& from_here,
+      const Closure& task,
+      WorkerShutdown shutdown_behavior);
+
+  // TaskRunner implementation. Forwards to PostDelayedWorkerTask().
+  virtual bool PostDelayedTask(const tracked_objects::Location& from_here,
+                               const Closure& task,
+                               TimeDelta delay) OVERRIDE;
+  virtual bool RunsTasksOnCurrentThread() const OVERRIDE;
+
+  // Returns true if the current thread is processing a task with the given
+  // sequence_token.
+  bool IsRunningSequenceOnCurrentThread(SequenceToken sequence_token) const;
+
+  // Blocks until all pending tasks are complete. This should only be called in
+  // unit tests when you want to validate something that should have happened.
+  // This will not flush delayed tasks; delayed tasks get deleted.
+  //
+  // Note that calling this will not prevent other threads from posting work to
+  // the queue while the calling thread is waiting on Flush(). In this case,
+  // Flush will return only when there's no more work in the queue. Normally,
+  // this doesn't come up since in a test, all the work is being posted from
+  // the main thread.
+  void FlushForTesting();
+
+  // Spuriously signal that there is work to be done.
+  void SignalHasWorkForTesting();
+
+  // Implements the worker pool shutdown. This should be called during app
+  // shutdown, and will discard/join with appropriate tasks before returning.
+  // After this call, subsequent calls to post tasks will fail.
+  //
+  // Must be called from the same thread this object was constructed on.
+  void Shutdown() { Shutdown(0); }
+
+  // A variant that allows an arbitrary number of new blocking tasks to
+  // be posted during shutdown from within tasks that execute during shutdown.
+  // Only tasks designated as BLOCKING_SHUTDOWN will be allowed, and only if
+  // posted by tasks that are not designated as CONTINUE_ON_SHUTDOWN. Once
+  // the limit is reached, subsequent calls to post task fail in all cases.
+  //
+  // Must be called from the same thread this object was constructed on.
+  void Shutdown(int max_new_blocking_tasks_after_shutdown);
+
+  // Check if Shutdown was called for given threading pool. This method is used
+  // for aborting time consuming operation to avoid blocking shutdown.
+  //
+  // Can be called from any thread.
+  bool IsShutdownInProgress();
+
+ protected:
+  virtual ~SequencedWorkerPool();
+
+  virtual void OnDestruct() const OVERRIDE;
+
+ private:
+  friend class RefCountedThreadSafe<SequencedWorkerPool>;
+  friend class DeleteHelper<SequencedWorkerPool>;
+
+  class Inner;
+  class Worker;
+
+  const scoped_refptr<MessageLoopProxy> constructor_message_loop_;
+
+  // Avoid pulling in too many headers by putting (almost) everything
+  // into |inner_|.
+  const scoped_ptr<Inner> inner_;
+
+  DISALLOW_COPY_AND_ASSIGN(SequencedWorkerPool);
+};
+
+}  // namespace base
+
+#endif  // BASE_THREADING_SEQUENCED_WORKER_POOL_H_
diff --git a/chromium/base/threading/sequenced_worker_pool_unittest.cc b/chromium/base/threading/sequenced_worker_pool_unittest.cc
new file mode 100644
index 00000000000..a07fd479095
--- /dev/null
+++ b/chromium/base/threading/sequenced_worker_pool_unittest.cc
@@ -0,0 +1,936 @@
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "base/threading/sequenced_worker_pool.h"
+
+#include <algorithm>
+
+#include "base/bind.h"
+#include "base/compiler_specific.h"
+#include "base/memory/ref_counted.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/message_loop/message_loop.h"
+#include "base/message_loop/message_loop_proxy.h"
+#include "base/synchronization/condition_variable.h"
+#include "base/synchronization/lock.h"
+#include "base/test/sequenced_task_runner_test_template.h"
+#include "base/test/sequenced_worker_pool_owner.h"
+#include "base/test/task_runner_test_template.h"
+#include "base/test/test_timeouts.h"
+#include "base/threading/platform_thread.h"
+#include "base/time/time.h"
+#include "base/tracked_objects.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace base {
+
+// IMPORTANT NOTE:
+//
+// Many of these tests have failure modes where they'll hang forever. These
+// tests should not be flaky, and hanging indicates a type of failure. Do not
+// mark as flaky if they're hanging, it's likely an actual bug.
+
+namespace {
+
+const size_t kNumWorkerThreads = 3;
+
+// Allows a number of threads to all be blocked on the same event, and
+// provides a way to unblock a certain number of them.
+class ThreadBlocker {
+ public:
+  ThreadBlocker() : lock_(), cond_var_(&lock_), unblock_counter_(0) {}
+
+  void Block() {
+    {
+      base::AutoLock lock(lock_);
+      while (unblock_counter_ == 0)
+        cond_var_.Wait();
+      unblock_counter_--;
+    }
+    cond_var_.Signal();
+  }
+
+  void Unblock(size_t count) {
+    {
+      base::AutoLock lock(lock_);
+      DCHECK(unblock_counter_ == 0);
+      unblock_counter_ = count;
+    }
+    cond_var_.Signal();
+  }
+
+ private:
+  base::Lock lock_;
+  base::ConditionVariable cond_var_;
+
+  size_t unblock_counter_;
+};
+
+class TestTracker : public base::RefCountedThreadSafe<TestTracker> {
+ public:
+  TestTracker()
+      : lock_(),
+        cond_var_(&lock_),
+        started_events_(0) {
+  }
+
+  // Each of these tasks appends the argument to the complete sequence vector
+  // so calling code can see what order they finished in.
+  void FastTask(int id) {
+    SignalWorkerDone(id);
+  }
+
+  void SlowTask(int id) {
+    base::PlatformThread::Sleep(base::TimeDelta::FromSeconds(1));
+    SignalWorkerDone(id);
+  }
+
+  void BlockTask(int id, ThreadBlocker* blocker) {
+    // Note that this task has started and signal anybody waiting for that
+    // to happen.
+    {
+      base::AutoLock lock(lock_);
+      started_events_++;
+    }
+    cond_var_.Signal();
+
+    blocker->Block();
+    SignalWorkerDone(id);
+  }
+
+  void PostAdditionalTasks(
+        int id, SequencedWorkerPool* pool,
+        bool expected_return_value) {
+    Closure fast_task = base::Bind(&TestTracker::FastTask, this, 100);
+    EXPECT_EQ(expected_return_value,
+              pool->PostWorkerTaskWithShutdownBehavior(
+                  FROM_HERE, fast_task,
+                  SequencedWorkerPool::CONTINUE_ON_SHUTDOWN));
+    EXPECT_EQ(expected_return_value,
+              pool->PostWorkerTaskWithShutdownBehavior(
+                  FROM_HERE, fast_task,
+                  SequencedWorkerPool::SKIP_ON_SHUTDOWN));
+    pool->PostWorkerTaskWithShutdownBehavior(
+        FROM_HERE, fast_task,
+        SequencedWorkerPool::BLOCK_SHUTDOWN);
+    SignalWorkerDone(id);
+  }
+
+  // Waits until the given number of tasks have started executing.
+  void WaitUntilTasksBlocked(size_t count) {
+    {
+      base::AutoLock lock(lock_);
+      while (started_events_ < count)
+        cond_var_.Wait();
+    }
+    cond_var_.Signal();
+  }
+
+  // Blocks the current thread until at least the given number of tasks are in
+  // the completed vector, and then returns a copy.
+  std::vector<int> WaitUntilTasksComplete(size_t num_tasks) {
+    std::vector<int> ret;
+    {
+      base::AutoLock lock(lock_);
+      while (complete_sequence_.size() < num_tasks)
+        cond_var_.Wait();
+      ret = complete_sequence_;
+    }
+    cond_var_.Signal();
+    return ret;
+  }
+
+  size_t GetTasksCompletedCount() {
+    base::AutoLock lock(lock_);
+    return complete_sequence_.size();
+  }
+
+  void ClearCompleteSequence() {
+    base::AutoLock lock(lock_);
+    complete_sequence_.clear();
+    started_events_ = 0;
+  }
+
+ private:
+  friend class base::RefCountedThreadSafe<TestTracker>;
+  ~TestTracker() {}
+
+  void SignalWorkerDone(int id) {
+    {
+      base::AutoLock lock(lock_);
+      complete_sequence_.push_back(id);
+    }
+    cond_var_.Signal();
+  }
+
+  // Protects the complete_sequence.
+  base::Lock lock_;
+
+  base::ConditionVariable cond_var_;
+
+  // Protected by lock_.
+  std::vector<int> complete_sequence_;
+
+  // Counter of the number of "block" workers that have started.
+  size_t started_events_;
+};
+
+class SequencedWorkerPoolTest : public testing::Test {
+ public:
+  SequencedWorkerPoolTest()
+      : tracker_(new TestTracker) {
+    ResetPool();
+  }
+
+  virtual ~SequencedWorkerPoolTest() {}
+
+  virtual void SetUp() OVERRIDE {}
+
+  virtual void TearDown() OVERRIDE {
+    pool()->Shutdown();
+  }
+
+  const scoped_refptr<SequencedWorkerPool>& pool() {
+    return pool_owner_->pool();
+  }
+  TestTracker* tracker() { return tracker_.get(); }
+
+  // Destroys the SequencedWorkerPool instance, blocking until it is fully shut
+  // down, and creates a new instance.
+  void ResetPool() {
+    pool_owner_.reset(new SequencedWorkerPoolOwner(kNumWorkerThreads, "test"));
+  }
+
+  void SetWillWaitForShutdownCallback(const Closure& callback) {
+    pool_owner_->SetWillWaitForShutdownCallback(callback);
+  }
+
+  // Ensures that the given number of worker threads is created by adding
+  // tasks and waiting until they complete. Worker thread creation is
+  // serialized, can happen on background threads asynchronously, and doesn't
+  // happen any more at shutdown. This means that if a test posts a bunch of
+  // tasks and calls shutdown, fewer workers will be created than the test may
+  // expect.
+  //
+  // This function ensures that this condition can't happen so tests can make
+  // assumptions about the number of workers active. See the comment in
+  // PrepareToStartAdditionalThreadIfNecessary in the .cc file for more
+  // details.
+  //
+  // It will post tasks to the queue with id -1. It also assumes this is the
+  // first thing called in a test since it will clear the complete_sequence_.
+  void EnsureAllWorkersCreated() {
+    // Create a bunch of threads, all waiting. This will cause that may
+    // workers to be created.
+    ThreadBlocker blocker;
+    for (size_t i = 0; i < kNumWorkerThreads; i++) {
+      pool()->PostWorkerTask(FROM_HERE,
+                             base::Bind(&TestTracker::BlockTask,
+                                        tracker(), -1, &blocker));
+    }
+    tracker()->WaitUntilTasksBlocked(kNumWorkerThreads);
+
+    // Now wake them up and wait until they're done.
+    blocker.Unblock(kNumWorkerThreads);
+    tracker()->WaitUntilTasksComplete(kNumWorkerThreads);
+
+    // Clean up the task IDs we added.
+    tracker()->ClearCompleteSequence();
+  }
+
+  int has_work_call_count() const {
+    return pool_owner_->has_work_call_count();
+  }
+
+ private:
+  MessageLoop message_loop_;
+  scoped_ptr<SequencedWorkerPoolOwner> pool_owner_;
+  const scoped_refptr<TestTracker> tracker_;
+};
+
+// Checks that the given number of entries are in the tasks to complete of
+// the given tracker, and then signals the given event the given number of
+// times. This is used to wakt up blocked background threads before blocking
+// on shutdown.
+void EnsureTasksToCompleteCountAndUnblock(scoped_refptr<TestTracker> tracker,
+                                          size_t expected_tasks_to_complete,
+                                          ThreadBlocker* blocker,
+                                          size_t threads_to_awake) {
+  EXPECT_EQ(
+      expected_tasks_to_complete,
+      tracker->WaitUntilTasksComplete(expected_tasks_to_complete).size());
+
+  blocker->Unblock(threads_to_awake);
+}
+
+class DeletionHelper : public base::RefCountedThreadSafe<DeletionHelper> {
+ public:
+  explicit DeletionHelper(
+      const scoped_refptr<base::RefCountedData<bool> >& deleted_flag)
+      : deleted_flag_(deleted_flag) {
+  }
+
+ private:
+  friend class base::RefCountedThreadSafe<DeletionHelper>;
+  virtual ~DeletionHelper() { deleted_flag_->data = true; }
+
+  const scoped_refptr<base::RefCountedData<bool> > deleted_flag_;
+  DISALLOW_COPY_AND_ASSIGN(DeletionHelper);
+};
+
+void HoldPoolReference(const scoped_refptr<base::SequencedWorkerPool>& pool,
+                       const scoped_refptr<DeletionHelper>& helper) {
+  ADD_FAILURE() << "Should never run";
+}
+
+// Tests that delayed tasks are deleted upon shutdown of the pool.
+TEST_F(SequencedWorkerPoolTest, DelayedTaskDuringShutdown) {
+  // Post something to verify the pool is started up.
+  EXPECT_TRUE(pool()->PostTask(
+      FROM_HERE, base::Bind(&TestTracker::FastTask, tracker(), 1)));
+
+  scoped_refptr<base::RefCountedData<bool> > deleted_flag(
+      new base::RefCountedData<bool>(false));
+
+  base::Time posted_at(base::Time::Now());
+  // Post something that shouldn't run.
+  EXPECT_TRUE(pool()->PostDelayedTask(
+      FROM_HERE,
+      base::Bind(&HoldPoolReference,
+                 pool(),
+                 make_scoped_refptr(new DeletionHelper(deleted_flag))),
+      TestTimeouts::action_timeout()));
+
+  std::vector<int> completion_sequence = tracker()->WaitUntilTasksComplete(1);
+  ASSERT_EQ(1u, completion_sequence.size());
+  ASSERT_EQ(1, completion_sequence[0]);
+
+  pool()->Shutdown();
+  // Shutdown is asynchronous, so use ResetPool() to block until the pool is
+  // fully destroyed (and thus shut down).
+  ResetPool();
+
+  // Verify that we didn't block until the task was due.
+  ASSERT_LT(base::Time::Now() - posted_at, TestTimeouts::action_timeout());
+
+  // Verify that the deferred task has not only not run, but has also been
+  // destroyed.
+  ASSERT_TRUE(deleted_flag->data);
+}
+
+// Tests that same-named tokens have the same ID.
+TEST_F(SequencedWorkerPoolTest, NamedTokens) {
+  const std::string name1("hello");
+  SequencedWorkerPool::SequenceToken token1 =
+      pool()->GetNamedSequenceToken(name1);
+
+  SequencedWorkerPool::SequenceToken token2 = pool()->GetSequenceToken();
+
+  const std::string name3("goodbye");
+  SequencedWorkerPool::SequenceToken token3 =
+      pool()->GetNamedSequenceToken(name3);
+
+  // All 3 tokens should be different.
+  EXPECT_FALSE(token1.Equals(token2));
+  EXPECT_FALSE(token1.Equals(token3));
+  EXPECT_FALSE(token2.Equals(token3));
+
+  // Requesting the same name again should give the same value.
+  SequencedWorkerPool::SequenceToken token1again =
+      pool()->GetNamedSequenceToken(name1);
+  EXPECT_TRUE(token1.Equals(token1again));
+
+  SequencedWorkerPool::SequenceToken token3again =
+      pool()->GetNamedSequenceToken(name3);
+  EXPECT_TRUE(token3.Equals(token3again));
+}
+
+// Tests that posting a bunch of tasks (many more than the number of worker
+// threads) runs them all.
+TEST_F(SequencedWorkerPoolTest, LotsOfTasks) {
+  pool()->PostWorkerTask(FROM_HERE,
+                         base::Bind(&TestTracker::SlowTask, tracker(), 0));
+
+  const size_t kNumTasks = 20;
+  for (size_t i = 1; i < kNumTasks; i++) {
+    pool()->PostWorkerTask(FROM_HERE,
+                           base::Bind(&TestTracker::FastTask, tracker(), i));
+  }
+
+  std::vector<int> result = tracker()->WaitUntilTasksComplete(kNumTasks);
+  EXPECT_EQ(kNumTasks, result.size());
+}
+
+// Tests that posting a bunch of tasks (many more than the number of
+// worker threads) to two pools simultaneously runs them all twice.
+// This test is meant to shake out any concurrency issues between
+// pools (like histograms).
+TEST_F(SequencedWorkerPoolTest, LotsOfTasksTwoPools) {
+  SequencedWorkerPoolOwner pool1(kNumWorkerThreads, "test1");
+  SequencedWorkerPoolOwner pool2(kNumWorkerThreads, "test2");
+
+  base::Closure slow_task = base::Bind(&TestTracker::SlowTask, tracker(), 0);
+  pool1.pool()->PostWorkerTask(FROM_HERE, slow_task);
+  pool2.pool()->PostWorkerTask(FROM_HERE, slow_task);
+
+  const size_t kNumTasks = 20;
+  for (size_t i = 1; i < kNumTasks; i++) {
+    base::Closure fast_task =
+        base::Bind(&TestTracker::FastTask, tracker(), i);
+    pool1.pool()->PostWorkerTask(FROM_HERE, fast_task);
+    pool2.pool()->PostWorkerTask(FROM_HERE, fast_task);
+  }
+
+  std::vector<int> result =
+      tracker()->WaitUntilTasksComplete(2*kNumTasks);
+  EXPECT_EQ(2 * kNumTasks, result.size());
+
+  pool2.pool()->Shutdown();
+  pool1.pool()->Shutdown();
+}
+
+// Test that tasks with the same sequence token are executed in order but don't
+// affect other tasks.
+TEST_F(SequencedWorkerPoolTest, Sequence) {
+  // Fill all the worker threads except one.
+  const size_t kNumBackgroundTasks = kNumWorkerThreads - 1;
+  ThreadBlocker background_blocker;
+  for (size_t i = 0; i < kNumBackgroundTasks; i++) {
+    pool()->PostWorkerTask(FROM_HERE,
+                           base::Bind(&TestTracker::BlockTask,
+                                      tracker(), i, &background_blocker));
+  }
+  tracker()->WaitUntilTasksBlocked(kNumBackgroundTasks);
+
+  // Create two tasks with the same sequence token, one that will block on the
+  // event, and one which will just complete quickly when it's run. Since there
+  // is one worker thread free, the first task will start and then block, and
+  // the second task should be waiting.
+  ThreadBlocker blocker;
+  SequencedWorkerPool::SequenceToken token1 = pool()->GetSequenceToken();
+  pool()->PostSequencedWorkerTask(
+      token1, FROM_HERE,
+      base::Bind(&TestTracker::BlockTask, tracker(), 100, &blocker));
+  pool()->PostSequencedWorkerTask(
+      token1, FROM_HERE,
+      base::Bind(&TestTracker::FastTask, tracker(), 101));
+  EXPECT_EQ(0u, tracker()->WaitUntilTasksComplete(0).size());
+
+  // Create another two tasks as above with a different token. These will be
+  // blocked since there are no slots to run.
+  SequencedWorkerPool::SequenceToken token2 = pool()->GetSequenceToken();
+  pool()->PostSequencedWorkerTask(
+      token2, FROM_HERE,
+      base::Bind(&TestTracker::FastTask, tracker(), 200));
+  pool()->PostSequencedWorkerTask(
+      token2, FROM_HERE,
+      base::Bind(&TestTracker::FastTask, tracker(), 201));
+  EXPECT_EQ(0u, tracker()->WaitUntilTasksComplete(0).size());
+
+  // Let one background task complete. This should then let both tasks of
+  // token2 run to completion in order. The second task of token1 should still
+  // be blocked.
+  background_blocker.Unblock(1);
+  std::vector<int> result = tracker()->WaitUntilTasksComplete(3);
+  ASSERT_EQ(3u, result.size());
+  EXPECT_EQ(200, result[1]);
+  EXPECT_EQ(201, result[2]);
+
+  // Finish the rest of the background tasks. This should leave some workers
+  // free with the second token1 task still blocked on the first.
+  background_blocker.Unblock(kNumBackgroundTasks - 1);
+  EXPECT_EQ(kNumBackgroundTasks + 2,
+            tracker()->WaitUntilTasksComplete(kNumBackgroundTasks + 2).size());
+
+  // Allow the first task of token1 to complete. This should run the second.
+  blocker.Unblock(1);
+  result = tracker()->WaitUntilTasksComplete(kNumBackgroundTasks + 4);
+  ASSERT_EQ(kNumBackgroundTasks + 4, result.size());
+  EXPECT_EQ(100, result[result.size() - 2]);
+  EXPECT_EQ(101, result[result.size() - 1]);
+}
+
+// Tests that any tasks posted after Shutdown are ignored.
+// Disabled for flakiness.  See http://crbug.com/166451.
+TEST_F(SequencedWorkerPoolTest, DISABLED_IgnoresAfterShutdown) {
+  // Start tasks to take all the threads and block them.
+  EnsureAllWorkersCreated();
+  ThreadBlocker blocker;
+  for (size_t i = 0; i < kNumWorkerThreads; i++) {
+    pool()->PostWorkerTask(FROM_HERE,
+                           base::Bind(&TestTracker::BlockTask,
+                                      tracker(), i, &blocker));
+  }
+  tracker()->WaitUntilTasksBlocked(kNumWorkerThreads);
+
+  SetWillWaitForShutdownCallback(
+      base::Bind(&EnsureTasksToCompleteCountAndUnblock,
+                 scoped_refptr<TestTracker>(tracker()), 0,
+                 &blocker, kNumWorkerThreads));
+
+  // Shutdown the worker pool. This should discard all non-blocking tasks.
+  const int kMaxNewBlockingTasksAfterShutdown = 100;
+  pool()->Shutdown(kMaxNewBlockingTasksAfterShutdown);
+
+  int old_has_work_call_count = has_work_call_count();
+
+  std::vector<int> result =
+      tracker()->WaitUntilTasksComplete(kNumWorkerThreads);
+
+  // The kNumWorkerThread items should have completed, in no particular order.
+  ASSERT_EQ(kNumWorkerThreads, result.size());
+  for (size_t i = 0; i < kNumWorkerThreads; i++) {
+    EXPECT_TRUE(std::find(result.begin(), result.end(), static_cast<int>(i)) !=
+                result.end());
+  }
+
+  // No further tasks, regardless of shutdown mode, should be allowed.
+  EXPECT_FALSE(pool()->PostWorkerTaskWithShutdownBehavior(
+      FROM_HERE,
+      base::Bind(&TestTracker::FastTask, tracker(), 100),
+      SequencedWorkerPool::CONTINUE_ON_SHUTDOWN));
+  EXPECT_FALSE(pool()->PostWorkerTaskWithShutdownBehavior(
+      FROM_HERE,
+      base::Bind(&TestTracker::FastTask, tracker(), 101),
+      SequencedWorkerPool::SKIP_ON_SHUTDOWN));
+  EXPECT_FALSE(pool()->PostWorkerTaskWithShutdownBehavior(
+      FROM_HERE,
+      base::Bind(&TestTracker::FastTask, tracker(), 102),
+      SequencedWorkerPool::BLOCK_SHUTDOWN));
+
+  ASSERT_EQ(old_has_work_call_count, has_work_call_count());
+}
+
+TEST_F(SequencedWorkerPoolTest, AllowsAfterShutdown) {
+  // Test that <n> new blocking tasks are allowed provided they're posted
+  // by a running tasks.
+  EnsureAllWorkersCreated();
+  ThreadBlocker blocker;
+
+  // Start tasks to take all the threads and block them.
+  const int kNumBlockTasks = static_cast<int>(kNumWorkerThreads);
+  for (int i = 0; i < kNumBlockTasks; ++i) {
+    EXPECT_TRUE(pool()->PostWorkerTask(
+        FROM_HERE,
+        base::Bind(&TestTracker::BlockTask, tracker(), i, &blocker)));
+  }
+  tracker()->WaitUntilTasksBlocked(kNumWorkerThreads);
+
+  // Queue up shutdown blocking tasks behind those which will attempt to post
+  // additional tasks when run, PostAdditionalTasks attemtps to post 3
+  // new FastTasks, one for each shutdown_behavior.
+  const int kNumQueuedTasks = static_cast<int>(kNumWorkerThreads);
+  for (int i = 0; i < kNumQueuedTasks; ++i) {
+    EXPECT_TRUE(pool()->PostWorkerTaskWithShutdownBehavior(
+        FROM_HERE,
+        base::Bind(&TestTracker::PostAdditionalTasks, tracker(), i, pool(),
+                   false),
+        SequencedWorkerPool::BLOCK_SHUTDOWN));
+  }
+
+  // Setup to open the floodgates from within Shutdown().
+  SetWillWaitForShutdownCallback(
+      base::Bind(&EnsureTasksToCompleteCountAndUnblock,
+                 scoped_refptr<TestTracker>(tracker()),
+                 0, &blocker, kNumBlockTasks));
+
+  // Allow half of the additional blocking tasks thru.
+  const int kNumNewBlockingTasksToAllow = kNumWorkerThreads / 2;
+  pool()->Shutdown(kNumNewBlockingTasksToAllow);
+
+  // Ensure that the correct number of tasks actually got run.
+  tracker()->WaitUntilTasksComplete(static_cast<size_t>(
+      kNumBlockTasks + kNumQueuedTasks + kNumNewBlockingTasksToAllow));
+
+  // Clean up the task IDs we added and go home.
+  tracker()->ClearCompleteSequence();
+}
+
+// Tests that unrun tasks are discarded properly according to their shutdown
+// mode.
+TEST_F(SequencedWorkerPoolTest, DiscardOnShutdown) {
+  // Start tasks to take all the threads and block them.
+  EnsureAllWorkersCreated();
+  ThreadBlocker blocker;
+  for (size_t i = 0; i < kNumWorkerThreads; i++) {
+    pool()->PostWorkerTask(FROM_HERE,
+                           base::Bind(&TestTracker::BlockTask,
+                                      tracker(), i, &blocker));
+  }
+  tracker()->WaitUntilTasksBlocked(kNumWorkerThreads);
+
+  // Create some tasks with different shutdown modes.
+  pool()->PostWorkerTaskWithShutdownBehavior(
+      FROM_HERE,
+      base::Bind(&TestTracker::FastTask, tracker(), 100),
+      SequencedWorkerPool::CONTINUE_ON_SHUTDOWN);
+  pool()->PostWorkerTaskWithShutdownBehavior(
+      FROM_HERE,
+      base::Bind(&TestTracker::FastTask, tracker(), 101),
+      SequencedWorkerPool::SKIP_ON_SHUTDOWN);
+  pool()->PostWorkerTaskWithShutdownBehavior(
+      FROM_HERE,
+      base::Bind(&TestTracker::FastTask, tracker(), 102),
+      SequencedWorkerPool::BLOCK_SHUTDOWN);
+
+  // Shutdown the worker pool. This should discard all non-blocking tasks.
+  SetWillWaitForShutdownCallback(
+      base::Bind(&EnsureTasksToCompleteCountAndUnblock,
+                 scoped_refptr<TestTracker>(tracker()), 0,
+                 &blocker, kNumWorkerThreads));
+  pool()->Shutdown();
+
+  std::vector<int> result =
+      tracker()->WaitUntilTasksComplete(kNumWorkerThreads + 1);
+
+  // The kNumWorkerThread items should have completed, plus the BLOCK_SHUTDOWN
+  // one, in no particular order.
+  ASSERT_EQ(kNumWorkerThreads + 1, result.size());
+  for (size_t i = 0; i < kNumWorkerThreads; i++) {
+    EXPECT_TRUE(std::find(result.begin(), result.end(), static_cast<int>(i)) !=
+                result.end());
+  }
+  EXPECT_TRUE(std::find(result.begin(), result.end(), 102) != result.end());
+}
+
+// Tests that CONTINUE_ON_SHUTDOWN tasks don't block shutdown.
+TEST_F(SequencedWorkerPoolTest, ContinueOnShutdown) {
+  scoped_refptr<TaskRunner> runner(pool()->GetTaskRunnerWithShutdownBehavior(
+      SequencedWorkerPool::CONTINUE_ON_SHUTDOWN));
+  scoped_refptr<SequencedTaskRunner> sequenced_runner(
+      pool()->GetSequencedTaskRunnerWithShutdownBehavior(
+          pool()->GetSequenceToken(),
+          SequencedWorkerPool::CONTINUE_ON_SHUTDOWN));
+  EnsureAllWorkersCreated();
+  ThreadBlocker blocker;
+  pool()->PostWorkerTaskWithShutdownBehavior(
+      FROM_HERE,
+      base::Bind(&TestTracker::BlockTask,
+                 tracker(), 0, &blocker),
+      SequencedWorkerPool::CONTINUE_ON_SHUTDOWN);
+  runner->PostTask(
+      FROM_HERE,
+      base::Bind(&TestTracker::BlockTask,
+                 tracker(), 1, &blocker));
+  sequenced_runner->PostTask(
+      FROM_HERE,
+      base::Bind(&TestTracker::BlockTask,
+                 tracker(), 2, &blocker));
+
+  tracker()->WaitUntilTasksBlocked(3);
+
+  // This should not block. If this test hangs, it means it failed.
+  pool()->Shutdown();
+
+  // The task should not have completed yet.
+  EXPECT_EQ(0u, tracker()->WaitUntilTasksComplete(0).size());
+
+  // Posting more tasks should fail.
+  EXPECT_FALSE(pool()->PostWorkerTaskWithShutdownBehavior(
+      FROM_HERE, base::Bind(&TestTracker::FastTask, tracker(), 0),
+      SequencedWorkerPool::CONTINUE_ON_SHUTDOWN));
+  EXPECT_FALSE(runner->PostTask(
+      FROM_HERE, base::Bind(&TestTracker::FastTask, tracker(), 0)));
+  EXPECT_FALSE(sequenced_runner->PostTask(
+      FROM_HERE, base::Bind(&TestTracker::FastTask, tracker(), 0)));
+
+  // Continue the background thread and make sure the tasks can complete.
+  blocker.Unblock(3);
+  std::vector<int> result = tracker()->WaitUntilTasksComplete(3);
+  EXPECT_EQ(3u, result.size());
+}
+
+// Tests that SKIP_ON_SHUTDOWN tasks that have been started block Shutdown
+// until they stop, but tasks not yet started do not.
+TEST_F(SequencedWorkerPoolTest, SkipOnShutdown) {
+  // Start tasks to take all the threads and block them.
+  EnsureAllWorkersCreated();
+  ThreadBlocker blocker;
+
+  // Now block all the threads with SKIP_ON_SHUTDOWN. Shutdown() should not
+  // return until these tasks have completed.
+  for (size_t i = 0; i < kNumWorkerThreads; i++) {
+    pool()->PostWorkerTaskWithShutdownBehavior(
+        FROM_HERE,
+        base::Bind(&TestTracker::BlockTask, tracker(), i, &blocker),
+        SequencedWorkerPool::SKIP_ON_SHUTDOWN);
+  }
+  tracker()->WaitUntilTasksBlocked(kNumWorkerThreads);
+
+  // Now post an additional task as SKIP_ON_SHUTDOWN, which should not be
+  // executed once Shutdown() has been called.
+  pool()->PostWorkerTaskWithShutdownBehavior(
+      FROM_HERE,
+      base::Bind(&TestTracker::BlockTask,
+                 tracker(), 0, &blocker),
+      SequencedWorkerPool::SKIP_ON_SHUTDOWN);
+
+  // This callback will only be invoked if SKIP_ON_SHUTDOWN tasks that have
+  // been started block shutdown.
+  SetWillWaitForShutdownCallback(
+      base::Bind(&EnsureTasksToCompleteCountAndUnblock,
+                 scoped_refptr<TestTracker>(tracker()), 0,
+                 &blocker, kNumWorkerThreads));
+
+  // No tasks should have completed yet.
+  EXPECT_EQ(0u, tracker()->WaitUntilTasksComplete(0).size());
+
+  // This should not block. If this test hangs, it means it failed.
+  pool()->Shutdown();
+
+  // Shutdown should not return until all of the tasks have completed.
+  std::vector<int> result =
+      tracker()->WaitUntilTasksComplete(kNumWorkerThreads);
+
+  // Only tasks marked SKIP_ON_SHUTDOWN that were already started should be
+  // allowed to complete. No additional non-blocking tasks should have been
+  // started.
+  ASSERT_EQ(kNumWorkerThreads, result.size());
+  for (size_t i = 0; i < kNumWorkerThreads; i++) {
+    EXPECT_TRUE(std::find(result.begin(), result.end(), static_cast<int>(i)) !=
+                result.end());
+  }
+}
+
+// Ensure all worker threads are created, and then trigger a spurious
+// work signal. This shouldn't cause any other work signals to be
+// triggered. This is a regression test for http://crbug.com/117469.
+TEST_F(SequencedWorkerPoolTest, SpuriousWorkSignal) {
+  EnsureAllWorkersCreated();
+  int old_has_work_call_count = has_work_call_count();
+  pool()->SignalHasWorkForTesting();
+  // This is inherently racy, but can only produce false positives.
+  base::PlatformThread::Sleep(base::TimeDelta::FromMilliseconds(100));
+  EXPECT_EQ(old_has_work_call_count + 1, has_work_call_count());
+}
+
+void IsRunningOnCurrentThreadTask(
+    SequencedWorkerPool::SequenceToken test_positive_token,
+    SequencedWorkerPool::SequenceToken test_negative_token,
+    SequencedWorkerPool* pool,
+    SequencedWorkerPool* unused_pool) {
+  EXPECT_TRUE(pool->RunsTasksOnCurrentThread());
+  EXPECT_TRUE(pool->IsRunningSequenceOnCurrentThread(test_positive_token));
+  EXPECT_FALSE(pool->IsRunningSequenceOnCurrentThread(test_negative_token));
+  EXPECT_FALSE(unused_pool->RunsTasksOnCurrentThread());
+  EXPECT_FALSE(
+      unused_pool->IsRunningSequenceOnCurrentThread(test_positive_token));
+  EXPECT_FALSE(
+      unused_pool->IsRunningSequenceOnCurrentThread(test_negative_token));
+}
+
+// Verify correctness of the IsRunningSequenceOnCurrentThread method.
+TEST_F(SequencedWorkerPoolTest, IsRunningOnCurrentThread) {
+  SequencedWorkerPool::SequenceToken token1 = pool()->GetSequenceToken();
+  SequencedWorkerPool::SequenceToken token2 = pool()->GetSequenceToken();
+  SequencedWorkerPool::SequenceToken unsequenced_token;
+
+  scoped_refptr<SequencedWorkerPool> unused_pool =
+      new SequencedWorkerPool(2, "unused_pool");
+
+  EXPECT_FALSE(pool()->RunsTasksOnCurrentThread());
+  EXPECT_FALSE(pool()->IsRunningSequenceOnCurrentThread(token1));
+  EXPECT_FALSE(pool()->IsRunningSequenceOnCurrentThread(token2));
+  EXPECT_FALSE(pool()->IsRunningSequenceOnCurrentThread(unsequenced_token));
+  EXPECT_FALSE(unused_pool->RunsTasksOnCurrentThread());
+  EXPECT_FALSE(unused_pool->IsRunningSequenceOnCurrentThread(token1));
+  EXPECT_FALSE(unused_pool->IsRunningSequenceOnCurrentThread(token2));
+  EXPECT_FALSE(
+      unused_pool->IsRunningSequenceOnCurrentThread(unsequenced_token));
+
+  pool()->PostSequencedWorkerTask(
+      token1, FROM_HERE,
+      base::Bind(&IsRunningOnCurrentThreadTask,
+                 token1, token2, pool(), unused_pool));
+  pool()->PostSequencedWorkerTask(
+      token2, FROM_HERE,
+      base::Bind(&IsRunningOnCurrentThreadTask,
+                 token2, unsequenced_token, pool(), unused_pool));
+  pool()->PostWorkerTask(
+      FROM_HERE,
+      base::Bind(&IsRunningOnCurrentThreadTask,
+                 unsequenced_token, token1, pool(), unused_pool));
+  pool()->Shutdown();
+  unused_pool->Shutdown();
+}
+
+// Verify that FlushForTesting works as intended.
+TEST_F(SequencedWorkerPoolTest, FlushForTesting) {
+  // Should be fine to call on a new instance.
+  pool()->FlushForTesting();
+
+  // Queue up a bunch of work, including  a long delayed task and
+  // a task that produces additional tasks as an artifact.
+  pool()->PostDelayedWorkerTask(
+      FROM_HERE,
+      base::Bind(&TestTracker::FastTask, tracker(), 0),
+      TimeDelta::FromMinutes(5));
+  pool()->PostWorkerTask(FROM_HERE,
+                         base::Bind(&TestTracker::SlowTask, tracker(), 0));
+  const size_t kNumFastTasks = 20;
+  for (size_t i = 0; i < kNumFastTasks; i++) {
+    pool()->PostWorkerTask(FROM_HERE,
+                           base::Bind(&TestTracker::FastTask, tracker(), 0));
+  }
+  pool()->PostWorkerTask(
+      FROM_HERE,
+      base::Bind(&TestTracker::PostAdditionalTasks, tracker(), 0, pool(),
+                 true));
+
+  // We expect all except the delayed task to have been run. We verify all
+  // closures have been deleted by looking at the refcount of the
+  // tracker.
+  EXPECT_FALSE(tracker()->HasOneRef());
+  pool()->FlushForTesting();
+  EXPECT_TRUE(tracker()->HasOneRef());
+  EXPECT_EQ(1 + kNumFastTasks + 1 + 3, tracker()->GetTasksCompletedCount());
+
+  // Should be fine to call on an idle instance with all threads created, and
+  // spamming the method shouldn't deadlock or confuse the class.
+  pool()->FlushForTesting();
+  pool()->FlushForTesting();
+
+  // Should be fine to call after shutdown too.
+  pool()->Shutdown();
+  pool()->FlushForTesting();
+}
+
+TEST(SequencedWorkerPoolRefPtrTest, ShutsDownCleanWithContinueOnShutdown) {
+  MessageLoop loop;
+  scoped_refptr<SequencedWorkerPool> pool(new SequencedWorkerPool(3, "Pool"));
+  scoped_refptr<SequencedTaskRunner> task_runner =
+      pool->GetSequencedTaskRunnerWithShutdownBehavior(
+          pool->GetSequenceToken(),
+          base::SequencedWorkerPool::CONTINUE_ON_SHUTDOWN);
+
+  // Upon test exit, should shut down without hanging.
+  pool->Shutdown();
+}
+
+class SequencedWorkerPoolTaskRunnerTestDelegate {
+ public:
+  SequencedWorkerPoolTaskRunnerTestDelegate() {}
+
+  ~SequencedWorkerPoolTaskRunnerTestDelegate() {}
+
+  void StartTaskRunner() {
+    pool_owner_.reset(
+        new SequencedWorkerPoolOwner(10, "SequencedWorkerPoolTaskRunnerTest"));
+  }
+
+  scoped_refptr<SequencedWorkerPool> GetTaskRunner() {
+    return pool_owner_->pool();
+  }
+
+  void StopTaskRunner() {
+    // Make sure all tasks are run before shutting down. Delayed tasks are
+    // not run, they're simply deleted.
+    pool_owner_->pool()->FlushForTesting();
+    pool_owner_->pool()->Shutdown();
+    // Don't reset |pool_owner_| here, as the test may still hold a
+    // reference to the pool.
+  }
+
+  bool TaskRunnerHandlesNonZeroDelays() const {
+    return true;
+  }
+
+ private:
+  MessageLoop message_loop_;
+  scoped_ptr<SequencedWorkerPoolOwner> pool_owner_;
+};
+
+INSTANTIATE_TYPED_TEST_CASE_P(
+    SequencedWorkerPool, TaskRunnerTest,
+    SequencedWorkerPoolTaskRunnerTestDelegate);
+
+class SequencedWorkerPoolTaskRunnerWithShutdownBehaviorTestDelegate {
+ public:
+  SequencedWorkerPoolTaskRunnerWithShutdownBehaviorTestDelegate() {}
+
+  ~SequencedWorkerPoolTaskRunnerWithShutdownBehaviorTestDelegate() {
+  }
+
+  void StartTaskRunner() {
+    pool_owner_.reset(
+        new SequencedWorkerPoolOwner(10, "SequencedWorkerPoolTaskRunnerTest"));
+    task_runner_ = pool_owner_->pool()->GetTaskRunnerWithShutdownBehavior(
+        SequencedWorkerPool::BLOCK_SHUTDOWN);
+  }
+
+  scoped_refptr<TaskRunner> GetTaskRunner() {
+    return task_runner_;
+  }
+
+  void StopTaskRunner() {
+    // Make sure all tasks are run before shutting down. Delayed tasks are
+    // not run, they're simply deleted.
+    pool_owner_->pool()->FlushForTesting();
+    pool_owner_->pool()->Shutdown();
+    // Don't reset |pool_owner_| here, as the test may still hold a
+    // reference to the pool.
+  }
+
+  bool TaskRunnerHandlesNonZeroDelays() const {
+    return true;
+  }
+
+ private:
+  MessageLoop message_loop_;
+  scoped_ptr<SequencedWorkerPoolOwner> pool_owner_;
+  scoped_refptr<TaskRunner> task_runner_;
+};
+
+INSTANTIATE_TYPED_TEST_CASE_P(
+    SequencedWorkerPoolTaskRunner, TaskRunnerTest,
+    SequencedWorkerPoolTaskRunnerWithShutdownBehaviorTestDelegate);
+
+class SequencedWorkerPoolSequencedTaskRunnerTestDelegate {
+ public:
+  SequencedWorkerPoolSequencedTaskRunnerTestDelegate() {}
+
+  ~SequencedWorkerPoolSequencedTaskRunnerTestDelegate() {
+  }
+
+  void StartTaskRunner() {
+    pool_owner_.reset(new SequencedWorkerPoolOwner(
+        10, "SequencedWorkerPoolSequencedTaskRunnerTest"));
+    task_runner_ = pool_owner_->pool()->GetSequencedTaskRunner(
+        pool_owner_->pool()->GetSequenceToken());
+  }
+
+  scoped_refptr<SequencedTaskRunner> GetTaskRunner() {
+    return task_runner_;
+  }
+
+  void StopTaskRunner() {
+    // Make sure all tasks are run before shutting down. Delayed tasks are
+    // not run, they're simply deleted.
+    pool_owner_->pool()->FlushForTesting();
+    pool_owner_->pool()->Shutdown();
+    // Don't reset |pool_owner_| here, as the test may still hold a
+    // reference to the pool.
+  }
+
+  bool TaskRunnerHandlesNonZeroDelays() const {
+    return true;
+  }
+
+ private:
+  MessageLoop message_loop_;
+  scoped_ptr<SequencedWorkerPoolOwner> pool_owner_;
+  scoped_refptr<SequencedTaskRunner> task_runner_;
+};
+
+INSTANTIATE_TYPED_TEST_CASE_P(
+    SequencedWorkerPoolSequencedTaskRunner, TaskRunnerTest,
+    SequencedWorkerPoolSequencedTaskRunnerTestDelegate);
+
+INSTANTIATE_TYPED_TEST_CASE_P(
+    SequencedWorkerPoolSequencedTaskRunner, SequencedTaskRunnerTest,
+    SequencedWorkerPoolSequencedTaskRunnerTestDelegate);
+
+}  // namespace
+
+}  // namespace base
diff --git a/chromium/base/threading/simple_thread.cc b/chromium/base/threading/simple_thread.cc
new file mode 100644
index 00000000000..028d4f4ab23
--- /dev/null
+++ b/chromium/base/threading/simple_thread.cc
@@ -0,0 +1,159 @@
+// Copyright (c) 2010 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "base/threading/simple_thread.h"
+
+#include "base/logging.h"
+#include "base/strings/string_number_conversions.h"
+#include "base/threading/platform_thread.h"
+#include "base/threading/thread_restrictions.h"
+
+namespace base {
+
+SimpleThread::SimpleThread(const std::string& name_prefix)
+    : name_prefix_(name_prefix), name_(name_prefix),
+      thread_(), event_(true, false), tid_(0), joined_(false) {
+}
+
+SimpleThread::SimpleThread(const std::string& name_prefix,
+                           const Options& options)
+    : name_prefix_(name_prefix), name_(name_prefix), options_(options),
+      thread_(), event_(true, false), tid_(0), joined_(false) {
+}
+
+SimpleThread::~SimpleThread() {
+  DCHECK(HasBeenStarted()) << "SimpleThread was never started.";
+  DCHECK(HasBeenJoined()) << "SimpleThread destroyed without being Join()ed.";
+}
+
+void SimpleThread::Start() {
+  DCHECK(!HasBeenStarted()) << "Tried to Start a thread multiple times.";
+  bool success = PlatformThread::Create(options_.stack_size(), this, &thread_);
+  DCHECK(success);
+  base::ThreadRestrictions::ScopedAllowWait allow_wait;
+  event_.Wait();  // Wait for the thread to complete initialization.
+}
+
+void SimpleThread::Join() {
+  DCHECK(HasBeenStarted()) << "Tried to Join a never-started thread.";
+  DCHECK(!HasBeenJoined()) << "Tried to Join a thread multiple times.";
+  PlatformThread::Join(thread_);
+  joined_ = true;
+}
+
+bool SimpleThread::HasBeenStarted() {
+  base::ThreadRestrictions::ScopedAllowWait allow_wait;
+  return event_.IsSignaled();
+}
+
+void SimpleThread::ThreadMain() {
+  tid_ = PlatformThread::CurrentId();
+  // Construct our full name of the form "name_prefix_/TID".
+  name_.push_back('/');
+  name_.append(IntToString(tid_));
+  PlatformThread::SetName(name_.c_str());
+
+  // We've initialized our new thread, signal that we're done to Start().
+  event_.Signal();
+
+  Run();
+}
+
+DelegateSimpleThread::DelegateSimpleThread(Delegate* delegate,
+                                           const std::string& name_prefix)
+    : SimpleThread(name_prefix),
+      delegate_(delegate) {
+}
+
+DelegateSimpleThread::DelegateSimpleThread(Delegate* delegate,
+                                           const std::string& name_prefix,
+                                           const Options& options)
+    : SimpleThread(name_prefix, options),
+      delegate_(delegate) {
+}
+
+DelegateSimpleThread::~DelegateSimpleThread() {
+}
+
+void DelegateSimpleThread::Run() {
+  DCHECK(delegate_) << "Tried to call Run without a delegate (called twice?)";
+  delegate_->Run();
+  delegate_ = NULL;
+}
+
+DelegateSimpleThreadPool::DelegateSimpleThreadPool(
+    const std::string& name_prefix,
+    int num_threads)
+    : name_prefix_(name_prefix),
+      num_threads_(num_threads),
+      dry_(true, false) {
+}
+
+DelegateSimpleThreadPool::~DelegateSimpleThreadPool() {
+  DCHECK(threads_.empty());
+  DCHECK(delegates_.empty());
+  DCHECK(!dry_.IsSignaled());
+}
+
+void DelegateSimpleThreadPool::Start() {
+  DCHECK(threads_.empty()) << "Start() called with outstanding threads.";
+  for (int i = 0; i < num_threads_; ++i) {
+    DelegateSimpleThread* thread = new DelegateSimpleThread(this, name_prefix_);
+    thread->Start();
+    threads_.push_back(thread);
+  }
+}
+
+void DelegateSimpleThreadPool::JoinAll() {
+  DCHECK(!threads_.empty()) << "JoinAll() called with no outstanding threads.";
+
+  // Tell all our threads to quit their worker loop.
+  AddWork(NULL, num_threads_);
+
+  // Join and destroy all the worker threads.
+  for (int i = 0; i < num_threads_; ++i) {
+    threads_[i]->Join();
+    delete threads_[i];
+  }
+  threads_.clear();
+  DCHECK(delegates_.empty());
+}
+
+void DelegateSimpleThreadPool::AddWork(Delegate* delegate, int repeat_count) {
+  AutoLock locked(lock_);
+  for (int i = 0; i < repeat_count; ++i)
+    delegates_.push(delegate);
+  // If we were empty, signal that we have work now.
+  if (!dry_.IsSignaled())
+    dry_.Signal();
+}
+
+void DelegateSimpleThreadPool::Run() {
+  Delegate* work = NULL;
+
+  while (true) {
+    dry_.Wait();
+    {
+      AutoLock locked(lock_);
+      if (!dry_.IsSignaled())
+        continue;
+
+      DCHECK(!delegates_.empty());
+      work = delegates_.front();
+      delegates_.pop();
+
+      // Signal to any other threads that we're currently out of work.
+      if (delegates_.empty())
+        dry_.Reset();
+    }
+
+    // A NULL delegate pointer signals us to quit.
+    if (!work)
+      break;
+
+    work->Run();
+  }
+}
+
+}  // namespace base
diff --git a/chromium/base/threading/simple_thread.h b/chromium/base/threading/simple_thread.h
new file mode 100644
index 00000000000..df03ce1c813
--- /dev/null
+++ b/chromium/base/threading/simple_thread.h
@@ -0,0 +1,190 @@
+// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// WARNING: You should probably be using Thread (thread.h) instead.  Thread is
+//          Chrome's message-loop based Thread abstraction, and if you are a
+//          thread running in the browser, there will likely be assumptions
+//          that your thread will have an associated message loop.
+//
+// This is a simple thread interface that backs to a native operating system
+// thread.  You should use this only when you want a thread that does not have
+// an associated MessageLoop.  Unittesting is the best example of this.
+//
+// The simplest interface to use is DelegateSimpleThread, which will create
+// a new thread, and execute the Delegate's virtual Run() in this new thread
+// until it has completed, exiting the thread.
+//
+// NOTE: You *MUST* call Join on the thread to clean up the underlying thread
+// resources.  You are also responsible for destructing the SimpleThread object.
+// It is invalid to destroy a SimpleThread while it is running, or without
+// Start() having been called (and a thread never created).  The Delegate
+// object should live as long as a DelegateSimpleThread.
+//
+// Thread Safety: A SimpleThread is not completely thread safe.  It is safe to
+// access it from the creating thread or from the newly created thread.  This
+// implies that the creator thread should be the thread that calls Join.
+//
+// Example:
+//   class MyThreadRunner : public DelegateSimpleThread::Delegate { ... };
+//   MyThreadRunner runner;
+//   DelegateSimpleThread thread(&runner, "good_name_here");
+//   thread.Start();
+//   // Start will return after the Thread has been successfully started and
+//   // initialized.  The newly created thread will invoke runner->Run(), and
+//   // run until it returns.
+//   thread.Join();  // Wait until the thread has exited.  You *MUST* Join!
+//   // The SimpleThread object is still valid, however you may not call Join
+//   // or Start again.
+
+#ifndef BASE_THREADING_SIMPLE_THREAD_H_
+#define BASE_THREADING_SIMPLE_THREAD_H_
+
+#include <string>
+#include <queue>
+#include <vector>
+
+#include "base/base_export.h"
+#include "base/basictypes.h"
+#include "base/compiler_specific.h"
+#include "base/threading/platform_thread.h"
+#include "base/synchronization/lock.h"
+#include "base/synchronization/waitable_event.h"
+
+namespace base {
+
+// This is the base SimpleThread.  You can derive from it and implement the
+// virtual Run method, or you can use the DelegateSimpleThread interface.
+class BASE_EXPORT SimpleThread : public PlatformThread::Delegate {
+ public:
+  class BASE_EXPORT Options {
+   public:
+    Options() : stack_size_(0) { }
+    ~Options() { }
+
+    // We use the standard compiler-supplied copy constructor.
+
+    // A custom stack size, or 0 for the system default.
+    void set_stack_size(size_t size) { stack_size_ = size; }
+    size_t stack_size() const { return stack_size_; }
+   private:
+    size_t stack_size_;
+  };
+
+  // Create a SimpleThread.  |options| should be used to manage any specific
+  // configuration involving the thread creation and management.
+  // Every thread has a name, in the form of |name_prefix|/TID, for example
+  // "my_thread/321".  The thread will not be created until Start() is called.
+  explicit SimpleThread(const std::string& name_prefix);
+  SimpleThread(const std::string& name_prefix, const Options& options);
+
+  virtual ~SimpleThread();
+
+  virtual void Start();
+  virtual void Join();
+
+  // Subclasses should override the Run method.
+  virtual void Run() = 0;
+
+  // Return the thread name prefix, or "unnamed" if none was supplied.
+  std::string name_prefix() { return name_prefix_; }
+
+  // Return the completed name including TID, only valid after Start().
+  std::string name() { return name_; }
+
+  // Return the thread id, only valid after Start().
+  PlatformThreadId tid() { return tid_; }
+
+  // Return True if Start() has ever been called.
+  bool HasBeenStarted();
+
+  // Return True if Join() has evern been called.
+  bool HasBeenJoined() { return joined_; }
+
+  // Overridden from PlatformThread::Delegate:
+  virtual void ThreadMain() OVERRIDE;
+
+  // Only set priorities with a careful understanding of the consequences.
+  // This is meant for very limited use cases.
+  void SetThreadPriority(ThreadPriority priority) {
+    PlatformThread::SetThreadPriority(thread_, priority);
+  }
+
+ private:
+  const std::string name_prefix_;
+  std::string name_;
+  const Options options_;
+  PlatformThreadHandle thread_;  // PlatformThread handle, invalid after Join!
+  WaitableEvent event_;          // Signaled if Start() was ever called.
+  PlatformThreadId tid_;         // The backing thread's id.
+  bool joined_;                  // True if Join has been called.
+};
+
+class BASE_EXPORT DelegateSimpleThread : public SimpleThread {
+ public:
+  class BASE_EXPORT Delegate {
+   public:
+    Delegate() { }
+    virtual ~Delegate() { }
+    virtual void Run() = 0;
+  };
+
+  DelegateSimpleThread(Delegate* delegate,
+                       const std::string& name_prefix);
+  DelegateSimpleThread(Delegate* delegate,
+                       const std::string& name_prefix,
+                       const Options& options);
+
+  virtual ~DelegateSimpleThread();
+  virtual void Run() OVERRIDE;
+ private:
+  Delegate* delegate_;
+};
+
+// DelegateSimpleThreadPool allows you to start up a fixed number of threads,
+// and then add jobs which will be dispatched to the threads.  This is
+// convenient when you have a lot of small work that you want done
+// multi-threaded, but don't want to spawn a thread for each small bit of work.
+//
+// You just call AddWork() to add a delegate to the list of work to be done.
+// JoinAll() will make sure that all outstanding work is processed, and wait
+// for everything to finish.  You can reuse a pool, so you can call Start()
+// again after you've called JoinAll().
+class BASE_EXPORT DelegateSimpleThreadPool
+    : public DelegateSimpleThread::Delegate {
+ public:
+  typedef DelegateSimpleThread::Delegate Delegate;
+
+  DelegateSimpleThreadPool(const std::string& name_prefix, int num_threads);
+  virtual ~DelegateSimpleThreadPool();
+
+  // Start up all of the underlying threads, and start processing work if we
+  // have any.
+  void Start();
+
+  // Make sure all outstanding work is finished, and wait for and destroy all
+  // of the underlying threads in the pool.
+  void JoinAll();
+
+  // It is safe to AddWork() any time, before or after Start().
+  // Delegate* should always be a valid pointer, NULL is reserved internally.
+  void AddWork(Delegate* work, int repeat_count);
+  void AddWork(Delegate* work) {
+    AddWork(work, 1);
+  }
+
+  // We implement the Delegate interface, for running our internal threads.
+  virtual void Run() OVERRIDE;
+
+ private:
+  const std::string name_prefix_;
+  int num_threads_;
+  std::vector<DelegateSimpleThread*> threads_;
+  std::queue<Delegate*> delegates_;
+  base::Lock lock_;            // Locks delegates_
+  WaitableEvent dry_;    // Not signaled when there is no work to do.
+};
+
+}  // namespace base
+
+#endif  // BASE_THREADING_SIMPLE_THREAD_H_
diff --git a/chromium/base/threading/simple_thread_unittest.cc b/chromium/base/threading/simple_thread_unittest.cc
new file mode 100644
index 00000000000..a744b8d4588
--- /dev/null
+++ b/chromium/base/threading/simple_thread_unittest.cc
@@ -0,0 +1,170 @@
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "base/atomic_sequence_num.h"
+#include "base/strings/string_number_conversions.h"
+#include "base/synchronization/waitable_event.h"
+#include "base/threading/simple_thread.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace base {
+
+namespace {
+
+class SetIntRunner : public DelegateSimpleThread::Delegate {
+ public:
+  SetIntRunner(int* ptr, int val) : ptr_(ptr), val_(val) { }
+  virtual ~SetIntRunner() { }
+
+  virtual void Run() OVERRIDE {
+    *ptr_ = val_;
+  }
+
+ private:
+  int* ptr_;
+  int val_;
+};
+
+class WaitEventRunner : public DelegateSimpleThread::Delegate {
+ public:
+  explicit WaitEventRunner(WaitableEvent* event) : event_(event) { }
+  virtual ~WaitEventRunner() { }
+
+  virtual void Run() OVERRIDE {
+    EXPECT_FALSE(event_->IsSignaled());
+    event_->Signal();
+    EXPECT_TRUE(event_->IsSignaled());
+  }
+ private:
+  WaitableEvent* event_;
+};
+
+class SeqRunner : public DelegateSimpleThread::Delegate {
+ public:
+  explicit SeqRunner(AtomicSequenceNumber* seq) : seq_(seq) { }
+  virtual void Run() OVERRIDE {
+    seq_->GetNext();
+  }
+
+ private:
+  AtomicSequenceNumber* seq_;
+};
+
+// We count up on a sequence number, firing on the event when we've hit our
+// expected amount, otherwise we wait on the event.  This will ensure that we
+// have all threads outstanding until we hit our expected thread pool size.
+class VerifyPoolRunner : public DelegateSimpleThread::Delegate {
+ public:
+  VerifyPoolRunner(AtomicSequenceNumber* seq,
+                   int total, WaitableEvent* event)
+      : seq_(seq), total_(total), event_(event) { }
+
+  virtual void Run() OVERRIDE {
+    if (seq_->GetNext() == total_) {
+      event_->Signal();
+    } else {
+      event_->Wait();
+    }
+  }
+
+ private:
+  AtomicSequenceNumber* seq_;
+  int total_;
+  WaitableEvent* event_;
+};
+
+}  // namespace
+
+TEST(SimpleThreadTest, CreateAndJoin) {
+  int stack_int = 0;
+
+  SetIntRunner runner(&stack_int, 7);
+  EXPECT_EQ(0, stack_int);
+
+  DelegateSimpleThread thread(&runner, "int_setter");
+  EXPECT_FALSE(thread.HasBeenStarted());
+  EXPECT_FALSE(thread.HasBeenJoined());
+  EXPECT_EQ(0, stack_int);
+
+  thread.Start();
+  EXPECT_TRUE(thread.HasBeenStarted());
+  EXPECT_FALSE(thread.HasBeenJoined());
+
+  thread.Join();
+  EXPECT_TRUE(thread.HasBeenStarted());
+  EXPECT_TRUE(thread.HasBeenJoined());
+  EXPECT_EQ(7, stack_int);
+}
+
+TEST(SimpleThreadTest, WaitForEvent) {
+  // Create a thread, and wait for it to signal us.
+  WaitableEvent event(true, false);
+
+  WaitEventRunner runner(&event);
+  DelegateSimpleThread thread(&runner, "event_waiter");
+
+  EXPECT_FALSE(event.IsSignaled());
+  thread.Start();
+  event.Wait();
+  EXPECT_TRUE(event.IsSignaled());
+  thread.Join();
+}
+
+TEST(SimpleThreadTest, NamedWithOptions) {
+  WaitableEvent event(true, false);
+
+  WaitEventRunner runner(&event);
+  SimpleThread::Options options;
+  DelegateSimpleThread thread(&runner, "event_waiter", options);
+  EXPECT_EQ(thread.name_prefix(), "event_waiter");
+  EXPECT_FALSE(event.IsSignaled());
+
+  thread.Start();
+  EXPECT_EQ(thread.name_prefix(), "event_waiter");
+  EXPECT_EQ(thread.name(),
+            std::string("event_waiter/") + IntToString(thread.tid()));
+  event.Wait();
+
+  EXPECT_TRUE(event.IsSignaled());
+  thread.Join();
+
+  // We keep the name and tid, even after the thread is gone.
+  EXPECT_EQ(thread.name_prefix(), "event_waiter");
+  EXPECT_EQ(thread.name(),
+            std::string("event_waiter/") + IntToString(thread.tid()));
+}
+
+TEST(SimpleThreadTest, ThreadPool) {
+  AtomicSequenceNumber seq;
+  SeqRunner runner(&seq);
+  DelegateSimpleThreadPool pool("seq_runner", 10);
+
+  // Add work before we're running.
+  pool.AddWork(&runner, 300);
+
+  EXPECT_EQ(seq.GetNext(), 0);
+  pool.Start();
+
+  // Add work while we're running.
+  pool.AddWork(&runner, 300);
+
+  pool.JoinAll();
+
+  EXPECT_EQ(seq.GetNext(), 601);
+
+  // We can reuse our pool.  Verify that all 10 threads can actually run in
+  // parallel, so this test will only pass if there are actually 10 threads.
+  AtomicSequenceNumber seq2;
+  WaitableEvent event(true, false);
+  // Changing 9 to 10, for example, would cause us JoinAll() to never return.
+  VerifyPoolRunner verifier(&seq2, 9, &event);
+  pool.Start();
+
+  pool.AddWork(&verifier, 10);
+
+  pool.JoinAll();
+  EXPECT_EQ(seq2.GetNext(), 10);
+}
+
+}  // namespace base
diff --git a/chromium/base/threading/thread.cc b/chromium/base/threading/thread.cc
new file mode 100644
index 00000000000..00f303d3609
--- /dev/null
+++ b/chromium/base/threading/thread.cc
@@ -0,0 +1,221 @@
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "base/threading/thread.h"
+
+#include "base/bind.h"
+#include "base/lazy_instance.h"
+#include "base/third_party/dynamic_annotations/dynamic_annotations.h"
+#include "base/threading/thread_id_name_manager.h"
+#include "base/threading/thread_local.h"
+#include "base/threading/thread_restrictions.h"
+#include "base/synchronization/waitable_event.h"
+
+#if defined(OS_WIN)
+#include "base/win/scoped_com_initializer.h"
+#endif
+
+namespace base {
+
+namespace {
+
+// We use this thread-local variable to record whether or not a thread exited
+// because its Stop method was called.  This allows us to catch cases where
+// MessageLoop::QuitWhenIdle() is called directly, which is unexpected when
+// using a Thread to setup and run a MessageLoop.
+base::LazyInstance<base::ThreadLocalBoolean> lazy_tls_bool =
+    LAZY_INSTANCE_INITIALIZER;
+
+}  // namespace
+
+// This is used to trigger the message loop to exit.
+void ThreadQuitHelper() {
+  MessageLoop::current()->QuitWhenIdle();
+  Thread::SetThreadWasQuitProperly(true);
+}
+
+// Used to pass data to ThreadMain.  This structure is allocated on the stack
+// from within StartWithOptions.
+struct Thread::StartupData {
+  // We get away with a const reference here because of how we are allocated.
+  const Thread::Options& options;
+
+  // Used to synchronize thread startup.
+  WaitableEvent event;
+
+  explicit StartupData(const Options& opt)
+      : options(opt),
+        event(false, false) {}
+};
+
+Thread::Thread(const char* name)
+    :
+#if defined(OS_WIN)
+      com_status_(NONE),
+#endif
+      started_(false),
+      stopping_(false),
+      running_(false),
+      startup_data_(NULL),
+      thread_(0),
+      message_loop_(NULL),
+      thread_id_(kInvalidThreadId),
+      name_(name) {
+}
+
+Thread::~Thread() {
+  Stop();
+}
+
+bool Thread::Start() {
+  Options options;
+#if defined(OS_WIN)
+  if (com_status_ == STA)
+    options.message_loop_type = MessageLoop::TYPE_UI;
+#endif
+  return StartWithOptions(options);
+}
+
+bool Thread::StartWithOptions(const Options& options) {
+  DCHECK(!message_loop_);
+#if defined(OS_WIN)
+  DCHECK((com_status_ != STA) ||
+      (options.message_loop_type == MessageLoop::TYPE_UI));
+#endif
+
+  SetThreadWasQuitProperly(false);
+
+  StartupData startup_data(options);
+  startup_data_ = &startup_data;
+
+  if (!PlatformThread::Create(options.stack_size, this, &thread_)) {
+    DLOG(ERROR) << "failed to create thread";
+    startup_data_ = NULL;
+    return false;
+  }
+
+  // Wait for the thread to start and initialize message_loop_
+  base::ThreadRestrictions::ScopedAllowWait allow_wait;
+  startup_data.event.Wait();
+
+  // set it to NULL so we don't keep a pointer to some object on the stack.
+  startup_data_ = NULL;
+  started_ = true;
+
+  DCHECK(message_loop_);
+  return true;
+}
+
+void Thread::Stop() {
+  if (!started_)
+    return;
+
+  StopSoon();
+
+  // Wait for the thread to exit.
+  //
+  // TODO(darin): Unfortunately, we need to keep message_loop_ around until
+  // the thread exits.  Some consumers are abusing the API.  Make them stop.
+  //
+  PlatformThread::Join(thread_);
+
+  // The thread should NULL message_loop_ on exit.
+  DCHECK(!message_loop_);
+
+  // The thread no longer needs to be joined.
+  started_ = false;
+
+  stopping_ = false;
+}
+
+void Thread::StopSoon() {
+  // We should only be called on the same thread that started us.
+
+  // Reading thread_id_ without a lock can lead to a benign data race
+  // with ThreadMain, so we annotate it to stay silent under ThreadSanitizer.
+  DCHECK_NE(ANNOTATE_UNPROTECTED_READ(thread_id_), PlatformThread::CurrentId());
+
+  if (stopping_ || !message_loop_)
+    return;
+
+  stopping_ = true;
+  message_loop_->PostTask(FROM_HERE, base::Bind(&ThreadQuitHelper));
+}
+
+bool Thread::IsRunning() const {
+  return running_;
+}
+
+void Thread::SetPriority(ThreadPriority priority) {
+  // The thread must be started (and id known) for this to be
+  // compatible with all platforms.
+  DCHECK_NE(thread_id_, kInvalidThreadId);
+  PlatformThread::SetThreadPriority(thread_, priority);
+}
+
+void Thread::Run(MessageLoop* message_loop) {
+  message_loop->Run();
+}
+
+void Thread::SetThreadWasQuitProperly(bool flag) {
+  lazy_tls_bool.Pointer()->Set(flag);
+}
+
+bool Thread::GetThreadWasQuitProperly() {
+  bool quit_properly = true;
+#ifndef NDEBUG
+  quit_properly = lazy_tls_bool.Pointer()->Get();
+#endif
+  return quit_properly;
+}
+
+void Thread::ThreadMain() {
+  {
+    // The message loop for this thread.
+    MessageLoop message_loop(startup_data_->options.message_loop_type);
+
+    // Complete the initialization of our Thread object.
+    thread_id_ = PlatformThread::CurrentId();
+    PlatformThread::SetName(name_.c_str());
+    ANNOTATE_THREAD_NAME(name_.c_str());  // Tell the name to race detector.
+    message_loop.set_thread_name(name_);
+    message_loop_ = &message_loop;
+
+#if defined(OS_WIN)
+    scoped_ptr<win::ScopedCOMInitializer> com_initializer;
+    if (com_status_ != NONE) {
+      com_initializer.reset((com_status_ == STA) ?
+          new win::ScopedCOMInitializer() :
+          new win::ScopedCOMInitializer(win::ScopedCOMInitializer::kMTA));
+    }
+#endif
+
+    // Let the thread do extra initialization.
+    // Let's do this before signaling we are started.
+    Init();
+
+    running_ = true;
+    startup_data_->event.Signal();
+    // startup_data_ can't be touched anymore since the starting thread is now
+    // unlocked.
+
+    Run(message_loop_);
+    running_ = false;
+
+    // Let the thread do extra cleanup.
+    CleanUp();
+
+#if defined(OS_WIN)
+    com_initializer.reset();
+#endif
+
+    // Assert that MessageLoop::Quit was called by ThreadQuitHelper.
+    DCHECK(GetThreadWasQuitProperly());
+
+    // We can't receive messages anymore.
+    message_loop_ = NULL;
+  }
+}
+
+}  // namespace base
diff --git a/chromium/base/threading/thread.h b/chromium/base/threading/thread.h
new file mode 100644
index 00000000000..98831b82e5c
--- /dev/null
+++ b/chromium/base/threading/thread.h
@@ -0,0 +1,216 @@
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef BASE_THREADING_THREAD_H_
+#define BASE_THREADING_THREAD_H_
+
+#include <string>
+
+#include "base/base_export.h"
+#include "base/message_loop/message_loop.h"
+#include "base/message_loop/message_loop_proxy.h"
+#include "base/threading/platform_thread.h"
+
+namespace base {
+
+// A simple thread abstraction that establishes a MessageLoop on a new thread.
+// The consumer uses the MessageLoop of the thread to cause code to execute on
+// the thread.  When this object is destroyed the thread is terminated.  All
+// pending tasks queued on the thread's message loop will run to completion
+// before the thread is terminated.
+//
+// WARNING! SUBCLASSES MUST CALL Stop() IN THEIR DESTRUCTORS!  See ~Thread().
+//
+// After the thread is stopped, the destruction sequence is:
+//
+//  (1) Thread::CleanUp()
+//  (2) MessageLoop::~MessageLoop
+//  (3.b)    MessageLoop::DestructionObserver::WillDestroyCurrentMessageLoop
+class BASE_EXPORT Thread : PlatformThread::Delegate {
+ public:
+  struct Options {
+    Options() : message_loop_type(MessageLoop::TYPE_DEFAULT), stack_size(0) {}
+    Options(MessageLoop::Type type, size_t size)
+        : message_loop_type(type), stack_size(size) {}
+
+    // Specifies the type of message loop that will be allocated on the thread.
+    MessageLoop::Type message_loop_type;
+
+    // Specifies the maximum stack size that the thread is allowed to use.
+    // This does not necessarily correspond to the thread's initial stack size.
+    // A value of 0 indicates that the default maximum should be used.
+    size_t stack_size;
+  };
+
+  // Constructor.
+  // name is a display string to identify the thread.
+  explicit Thread(const char* name);
+
+  // Destroys the thread, stopping it if necessary.
+  //
+  // NOTE: ALL SUBCLASSES OF Thread MUST CALL Stop() IN THEIR DESTRUCTORS (or
+  // guarantee Stop() is explicitly called before the subclass is destroyed).
+  // This is required to avoid a data race between the destructor modifying the
+  // vtable, and the thread's ThreadMain calling the virtual method Run().  It
+  // also ensures that the CleanUp() virtual method is called on the subclass
+  // before it is destructed.
+  virtual ~Thread();
+
+#if defined(OS_WIN)
+  // Causes the thread to initialize COM.  This must be called before calling
+  // Start() or StartWithOptions().  If |use_mta| is false, the thread is also
+  // started with a TYPE_UI message loop.  It is an error to call
+  // init_com_with_mta(false) and then StartWithOptions() with any message loop
+  // type other than TYPE_UI.
+  void init_com_with_mta(bool use_mta) {
+    DCHECK(!started_);
+    com_status_ = use_mta ? MTA : STA;
+  }
+#endif
+
+  // Starts the thread.  Returns true if the thread was successfully started;
+  // otherwise, returns false.  Upon successful return, the message_loop()
+  // getter will return non-null.
+  //
+  // Note: This function can't be called on Windows with the loader lock held;
+  // i.e. during a DllMain, global object construction or destruction, atexit()
+  // callback.
+  bool Start();
+
+  // Starts the thread. Behaves exactly like Start in addition to allow to
+  // override the default options.
+  //
+  // Note: This function can't be called on Windows with the loader lock held;
+  // i.e. during a DllMain, global object construction or destruction, atexit()
+  // callback.
+  bool StartWithOptions(const Options& options);
+
+  // Signals the thread to exit and returns once the thread has exited.  After
+  // this method returns, the Thread object is completely reset and may be used
+  // as if it were newly constructed (i.e., Start may be called again).
+  //
+  // Stop may be called multiple times and is simply ignored if the thread is
+  // already stopped.
+  //
+  // NOTE: If you are a consumer of Thread, it is not necessary to call this
+  // before deleting your Thread objects, as the destructor will do it.
+  // IF YOU ARE A SUBCLASS OF Thread, YOU MUST CALL THIS IN YOUR DESTRUCTOR.
+  void Stop();
+
+  // Signals the thread to exit in the near future.
+  //
+  // WARNING: This function is not meant to be commonly used. Use at your own
+  // risk. Calling this function will cause message_loop() to become invalid in
+  // the near future. This function was created to workaround a specific
+  // deadlock on Windows with printer worker thread. In any other case, Stop()
+  // should be used.
+  //
+  // StopSoon should not be called multiple times as it is risky to do so. It
+  // could cause a timing issue in message_loop() access. Call Stop() to reset
+  // the thread object once it is known that the thread has quit.
+  void StopSoon();
+
+  // Returns the message loop for this thread.  Use the MessageLoop's
+  // PostTask methods to execute code on the thread.  This only returns
+  // non-null after a successful call to Start.  After Stop has been called,
+  // this will return NULL.
+  //
+  // NOTE: You must not call this MessageLoop's Quit method directly.  Use
+  // the Thread's Stop method instead.
+  //
+  MessageLoop* message_loop() const { return message_loop_; }
+
+  // Returns a MessageLoopProxy for this thread.  Use the MessageLoopProxy's
+  // PostTask methods to execute code on the thread.  This only returns
+  // non-NULL after a successful call to Start. After Stop has been called,
+  // this will return NULL. Callers can hold on to this even after the thread
+  // is gone.
+  scoped_refptr<MessageLoopProxy> message_loop_proxy() const {
+    return message_loop_ ? message_loop_->message_loop_proxy() : NULL;
+  }
+
+  // Returns the name of this thread (for display in debugger too).
+  const std::string& thread_name() const { return name_; }
+
+  // The native thread handle.
+  PlatformThreadHandle thread_handle() { return thread_; }
+
+  // The thread ID.
+  PlatformThreadId thread_id() const { return thread_id_; }
+
+  // Returns true if the thread has been started, and not yet stopped.
+  bool IsRunning() const;
+
+  // Sets the thread priority. The thread must already be started.
+  void SetPriority(ThreadPriority priority);
+
+ protected:
+  // Called just prior to starting the message loop
+  virtual void Init() {}
+
+  // Called to start the message loop
+  virtual void Run(MessageLoop* message_loop);
+
+  // Called just after the message loop ends
+  virtual void CleanUp() {}
+
+  static void SetThreadWasQuitProperly(bool flag);
+  static bool GetThreadWasQuitProperly();
+
+  void set_message_loop(MessageLoop* message_loop) {
+    message_loop_ = message_loop;
+  }
+
+ private:
+#if defined(OS_WIN)
+  enum ComStatus {
+    NONE,
+    STA,
+    MTA,
+  };
+#endif
+
+  // PlatformThread::Delegate methods:
+  virtual void ThreadMain() OVERRIDE;
+
+#if defined(OS_WIN)
+  // Whether this thread needs to initialize COM, and if so, in what mode.
+  ComStatus com_status_;
+#endif
+
+  // Whether we successfully started the thread.
+  bool started_;
+
+  // If true, we're in the middle of stopping, and shouldn't access
+  // |message_loop_|. It may non-NULL and invalid.
+  bool stopping_;
+
+  // True while inside of Run().
+  bool running_;
+
+  // Used to pass data to ThreadMain.
+  struct StartupData;
+  StartupData* startup_data_;
+
+  // The thread's handle.
+  PlatformThreadHandle thread_;
+
+  // The thread's message loop.  Valid only while the thread is alive.  Set
+  // by the created thread.
+  MessageLoop* message_loop_;
+
+  // Our thread's ID.
+  PlatformThreadId thread_id_;
+
+  // The name of the thread.  Used for debugging purposes.
+  std::string name_;
+
+  friend void ThreadQuitHelper();
+
+  DISALLOW_COPY_AND_ASSIGN(Thread);
+};
+
+}  // namespace base
+
+#endif  // BASE_THREADING_THREAD_H_
diff --git a/chromium/base/threading/thread_checker.h b/chromium/base/threading/thread_checker.h
new file mode 100644
index 00000000000..5a8ef2261d7
--- /dev/null
+++ b/chromium/base/threading/thread_checker.h
@@ -0,0 +1,85 @@
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef BASE_THREADING_THREAD_CHECKER_H_
+#define BASE_THREADING_THREAD_CHECKER_H_
+
+// Apart from debug builds, we also enable the thread checker in
+// builds with DCHECK_ALWAYS_ON so that trybots and waterfall bots
+// with this define will get the same level of thread checking as
+// debug bots.
+//
+// Note that this does not perfectly match situations where DCHECK is
+// enabled.  For example a non-official release build may have
+// DCHECK_ALWAYS_ON undefined (and therefore ThreadChecker would be
+// disabled) but have DCHECKs enabled at runtime.
+#if (!defined(NDEBUG) || defined(DCHECK_ALWAYS_ON))
+#define ENABLE_THREAD_CHECKER 1
+#else
+#define ENABLE_THREAD_CHECKER 0
+#endif
+
+#if ENABLE_THREAD_CHECKER
+#include "base/threading/thread_checker_impl.h"
+#endif
+
+namespace base {
+
+// Do nothing implementation, for use in release mode.
+//
+// Note: You should almost always use the ThreadChecker class to get the
+// right version for your build configuration.
+class ThreadCheckerDoNothing {
+ public:
+  bool CalledOnValidThread() const {
+    return true;
+  }
+
+  void DetachFromThread() {}
+};
+
+// ThreadChecker is a helper class used to help verify that some methods of a
+// class are called from the same thread. It provides identical functionality to
+// base::NonThreadSafe, but it is meant to be held as a member variable, rather
+// than inherited from base::NonThreadSafe.
+//
+// While inheriting from base::NonThreadSafe may give a clear indication about
+// the thread-safety of a class, it may also lead to violations of the style
+// guide with regard to multiple inheritence. The choice between having a
+// ThreadChecker member and inheriting from base::NonThreadSafe should be based
+// on whether:
+//  - Derived classes need to know the thread they belong to, as opposed to
+//    having that functionality fully encapsulated in the base class.
+//  - Derived classes should be able to reassign the base class to another
+//    thread, via DetachFromThread.
+//
+// If neither of these are true, then having a ThreadChecker member and calling
+// CalledOnValidThread is the preferable solution.
+//
+// Example:
+// class MyClass {
+//  public:
+//   void Foo() {
+//     DCHECK(thread_checker_.CalledOnValidThread());
+//     ... (do stuff) ...
+//   }
+//
+//  private:
+//   ThreadChecker thread_checker_;
+// }
+//
+// In Release mode, CalledOnValidThread will always return true.
+#if ENABLE_THREAD_CHECKER
+class ThreadChecker : public ThreadCheckerImpl {
+};
+#else
+class ThreadChecker : public ThreadCheckerDoNothing {
+};
+#endif  // ENABLE_THREAD_CHECKER
+
+#undef ENABLE_THREAD_CHECKER
+
+}  // namespace base
+
+#endif  // BASE_THREADING_THREAD_CHECKER_H_
diff --git a/chromium/base/threading/thread_checker_impl.cc b/chromium/base/threading/thread_checker_impl.cc
new file mode 100644
index 00000000000..985433e5f11
--- /dev/null
+++ b/chromium/base/threading/thread_checker_impl.cc
@@ -0,0 +1,34 @@
+// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "base/threading/thread_checker_impl.h"
+
+namespace base {
+
+ThreadCheckerImpl::ThreadCheckerImpl()
+    : valid_thread_id_(kInvalidThreadId) {
+  EnsureThreadIdAssigned();
+}
+
+ThreadCheckerImpl::~ThreadCheckerImpl() {}
+
+bool ThreadCheckerImpl::CalledOnValidThread() const {
+  EnsureThreadIdAssigned();
+  AutoLock auto_lock(lock_);
+  return valid_thread_id_ == PlatformThread::CurrentId();
+}
+
+void ThreadCheckerImpl::DetachFromThread() {
+  AutoLock auto_lock(lock_);
+  valid_thread_id_ = kInvalidThreadId;
+}
+
+void ThreadCheckerImpl::EnsureThreadIdAssigned() const {
+  AutoLock auto_lock(lock_);
+  if (valid_thread_id_ != kInvalidThreadId)
+    return;
+  valid_thread_id_ = PlatformThread::CurrentId();
+}
+
+}  // namespace base
diff --git a/chromium/base/threading/thread_checker_impl.h b/chromium/base/threading/thread_checker_impl.h
new file mode 100644
index 00000000000..24361c83221
--- /dev/null
+++ b/chromium/base/threading/thread_checker_impl.h
@@ -0,0 +1,43 @@
+// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef BASE_THREADING_THREAD_CHECKER_IMPL_H_
+#define BASE_THREADING_THREAD_CHECKER_IMPL_H_
+
+#include "base/base_export.h"
+#include "base/synchronization/lock.h"
+#include "base/threading/platform_thread.h"
+
+namespace base {
+
+// Real implementation of ThreadChecker, for use in debug mode, or
+// for temporary use in release mode (e.g. to CHECK on a threading issue
+// seen only in the wild).
+//
+// Note: You should almost always use the ThreadChecker class to get the
+// right version for your build configuration.
+class BASE_EXPORT ThreadCheckerImpl {
+ public:
+  ThreadCheckerImpl();
+  ~ThreadCheckerImpl();
+
+  bool CalledOnValidThread() const;
+
+  // Changes the thread that is checked for in CalledOnValidThread.  This may
+  // be useful when an object may be created on one thread and then used
+  // exclusively on another thread.
+  void DetachFromThread();
+
+ private:
+  void EnsureThreadIdAssigned() const;
+
+  mutable base::Lock lock_;
+  // This is mutable so that CalledOnValidThread can set it.
+  // It's guarded by |lock_|.
+  mutable PlatformThreadId valid_thread_id_;
+};
+
+}  // namespace base
+
+#endif  // BASE_THREADING_THREAD_CHECKER_IMPL_H_
diff --git a/chromium/base/threading/thread_checker_unittest.cc b/chromium/base/threading/thread_checker_unittest.cc
new file mode 100644
index 00000000000..ae96923e5ca
--- /dev/null
+++ b/chromium/base/threading/thread_checker_unittest.cc
@@ -0,0 +1,183 @@
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "base/basictypes.h"
+#include "base/logging.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/threading/thread_checker.h"
+#include "base/threading/simple_thread.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+// Duplicated from base/threading/thread_checker.h so that we can be
+// good citizens there and undef the macro.
+#if !defined(NDEBUG) || defined(DCHECK_ALWAYS_ON)
+#define ENABLE_THREAD_CHECKER 1
+#else
+#define ENABLE_THREAD_CHECKER 0
+#endif
+
+namespace base {
+
+namespace {
+
+// Simple class to exercise the basics of ThreadChecker.
+// Both the destructor and DoStuff should verify that they were
+// called on the same thread as the constructor.
+class ThreadCheckerClass : public ThreadChecker {
+ public:
+  ThreadCheckerClass() {}
+
+  // Verifies that it was called on the same thread as the constructor.
+  void DoStuff() {
+    DCHECK(CalledOnValidThread());
+  }
+
+  void DetachFromThread() {
+    ThreadChecker::DetachFromThread();
+  }
+
+  static void MethodOnDifferentThreadImpl();
+  static void DetachThenCallFromDifferentThreadImpl();
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(ThreadCheckerClass);
+};
+
+// Calls ThreadCheckerClass::DoStuff on another thread.
+class CallDoStuffOnThread : public base::SimpleThread {
+ public:
+  explicit CallDoStuffOnThread(ThreadCheckerClass* thread_checker_class)
+      : SimpleThread("call_do_stuff_on_thread"),
+        thread_checker_class_(thread_checker_class) {
+  }
+
+  virtual void Run() OVERRIDE {
+    thread_checker_class_->DoStuff();
+  }
+
+ private:
+  ThreadCheckerClass* thread_checker_class_;
+
+  DISALLOW_COPY_AND_ASSIGN(CallDoStuffOnThread);
+};
+
+// Deletes ThreadCheckerClass on a different thread.
+class DeleteThreadCheckerClassOnThread : public base::SimpleThread {
+ public:
+  explicit DeleteThreadCheckerClassOnThread(
+      ThreadCheckerClass* thread_checker_class)
+      : SimpleThread("delete_thread_checker_class_on_thread"),
+        thread_checker_class_(thread_checker_class) {
+  }
+
+  virtual void Run() OVERRIDE {
+    thread_checker_class_.reset();
+  }
+
+ private:
+  scoped_ptr<ThreadCheckerClass> thread_checker_class_;
+
+  DISALLOW_COPY_AND_ASSIGN(DeleteThreadCheckerClassOnThread);
+};
+
+}  // namespace
+
+TEST(ThreadCheckerTest, CallsAllowedOnSameThread) {
+  scoped_ptr<ThreadCheckerClass> thread_checker_class(
+      new ThreadCheckerClass);
+
+  // Verify that DoStuff doesn't assert.
+  thread_checker_class->DoStuff();
+
+  // Verify that the destructor doesn't assert.
+  thread_checker_class.reset();
+}
+
+TEST(ThreadCheckerTest, DestructorAllowedOnDifferentThread) {
+  scoped_ptr<ThreadCheckerClass> thread_checker_class(
+      new ThreadCheckerClass);
+
+  // Verify that the destructor doesn't assert
+  // when called on a different thread.
+  DeleteThreadCheckerClassOnThread delete_on_thread(
+      thread_checker_class.release());
+
+  delete_on_thread.Start();
+  delete_on_thread.Join();
+}
+
+TEST(ThreadCheckerTest, DetachFromThread) {
+  scoped_ptr<ThreadCheckerClass> thread_checker_class(
+      new ThreadCheckerClass);
+
+  // Verify that DoStuff doesn't assert when called on a different thread after
+  // a call to DetachFromThread.
+  thread_checker_class->DetachFromThread();
+  CallDoStuffOnThread call_on_thread(thread_checker_class.get());
+
+  call_on_thread.Start();
+  call_on_thread.Join();
+}
+
+#if GTEST_HAS_DEATH_TEST || !ENABLE_THREAD_CHECKER
+
+void ThreadCheckerClass::MethodOnDifferentThreadImpl() {
+  scoped_ptr<ThreadCheckerClass> thread_checker_class(
+      new ThreadCheckerClass);
+
+  // DoStuff should assert in debug builds only when called on a
+  // different thread.
+  CallDoStuffOnThread call_on_thread(thread_checker_class.get());
+
+  call_on_thread.Start();
+  call_on_thread.Join();
+}
+
+#if ENABLE_THREAD_CHECKER
+TEST(ThreadCheckerDeathTest, MethodNotAllowedOnDifferentThreadInDebug) {
+  ASSERT_DEATH({
+      ThreadCheckerClass::MethodOnDifferentThreadImpl();
+    }, "");
+}
+#else
+TEST(ThreadCheckerTest, MethodAllowedOnDifferentThreadInRelease) {
+  ThreadCheckerClass::MethodOnDifferentThreadImpl();
+}
+#endif  // ENABLE_THREAD_CHECKER
+
+void ThreadCheckerClass::DetachThenCallFromDifferentThreadImpl() {
+  scoped_ptr<ThreadCheckerClass> thread_checker_class(
+      new ThreadCheckerClass);
+
+  // DoStuff doesn't assert when called on a different thread
+  // after a call to DetachFromThread.
+  thread_checker_class->DetachFromThread();
+  CallDoStuffOnThread call_on_thread(thread_checker_class.get());
+
+  call_on_thread.Start();
+  call_on_thread.Join();
+
+  // DoStuff should assert in debug builds only after moving to
+  // another thread.
+  thread_checker_class->DoStuff();
+}
+
+#if ENABLE_THREAD_CHECKER
+TEST(ThreadCheckerDeathTest, DetachFromThreadInDebug) {
+  ASSERT_DEATH({
+    ThreadCheckerClass::DetachThenCallFromDifferentThreadImpl();
+    }, "");
+}
+#else
+TEST(ThreadCheckerTest, DetachFromThreadInRelease) {
+  ThreadCheckerClass::DetachThenCallFromDifferentThreadImpl();
+}
+#endif  // ENABLE_THREAD_CHECKER
+
+#endif  // GTEST_HAS_DEATH_TEST || !ENABLE_THREAD_CHECKER
+
+// Just in case we ever get lumped together with other compilation units.
+#undef ENABLE_THREAD_CHECKER
+
+}  // namespace base
diff --git a/chromium/base/threading/thread_collision_warner.cc b/chromium/base/threading/thread_collision_warner.cc
new file mode 100644
index 00000000000..547e11ca66f
--- /dev/null
+++ b/chromium/base/threading/thread_collision_warner.cc
@@ -0,0 +1,64 @@
+// Copyright (c) 2010 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "base/threading/thread_collision_warner.h"
+
+#include "base/logging.h"
+#include "base/threading/platform_thread.h"
+
+namespace base {
+
+void DCheckAsserter::warn() {
+  NOTREACHED() << "Thread Collision";
+}
+
+static subtle::Atomic32 CurrentThread() {
+  const PlatformThreadId current_thread_id = PlatformThread::CurrentId();
+  // We need to get the thread id into an atomic data type. This might be a
+  // truncating conversion, but any loss-of-information just increases the
+  // chance of a fault negative, not a false positive.
+  const subtle::Atomic32 atomic_thread_id =
+      static_cast<subtle::Atomic32>(current_thread_id);
+
+  return atomic_thread_id;
+}
+
+void ThreadCollisionWarner::EnterSelf() {
+  // If the active thread is 0 then I'll write the current thread ID
+  // if two or more threads arrive here only one will succeed to
+  // write on valid_thread_id_ the current thread ID.
+  subtle::Atomic32 current_thread_id = CurrentThread();
+
+  int previous_value = subtle::NoBarrier_CompareAndSwap(&valid_thread_id_,
+                                                        0,
+                                                        current_thread_id);
+  if (previous_value != 0 && previous_value != current_thread_id) {
+    // gotcha! a thread is trying to use the same class and that is
+    // not current thread.
+    asserter_->warn();
+  }
+
+  subtle::NoBarrier_AtomicIncrement(&counter_, 1);
+}
+
+void ThreadCollisionWarner::Enter() {
+  subtle::Atomic32 current_thread_id = CurrentThread();
+
+  if (subtle::NoBarrier_CompareAndSwap(&valid_thread_id_,
+                                       0,
+                                       current_thread_id) != 0) {
+    // gotcha! another thread is trying to use the same class.
+    asserter_->warn();
+  }
+
+  subtle::NoBarrier_AtomicIncrement(&counter_, 1);
+}
+
+void ThreadCollisionWarner::Leave() {
+  if (subtle::Barrier_AtomicIncrement(&counter_, -1) == 0) {
+    subtle::NoBarrier_Store(&valid_thread_id_, 0);
+  }
+}
+
+}  // namespace base
diff --git a/chromium/base/threading/thread_collision_warner.h b/chromium/base/threading/thread_collision_warner.h
new file mode 100644
index 00000000000..d509a58e8de
--- /dev/null
+++ b/chromium/base/threading/thread_collision_warner.h
@@ -0,0 +1,244 @@
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef BASE_THREADING_THREAD_COLLISION_WARNER_H_
+#define BASE_THREADING_THREAD_COLLISION_WARNER_H_
+
+#include <memory>
+
+#include "base/atomicops.h"
+#include "base/base_export.h"
+#include "base/compiler_specific.h"
+
+// A helper class alongside macros to be used to verify assumptions about thread
+// safety of a class.
+//
+// Example: Queue implementation non thread-safe but still usable if clients
+//          are synchronized somehow.
+//
+//          In this case the macro DFAKE_SCOPED_LOCK has to be
+//          used, it checks that if a thread is inside the push/pop then
+//          noone else is still inside the pop/push
+//
+// class NonThreadSafeQueue {
+//  public:
+//   ...
+//   void push(int) { DFAKE_SCOPED_LOCK(push_pop_); ... }
+//   int pop() { DFAKE_SCOPED_LOCK(push_pop_); ... }
+//   ...
+//  private:
+//   DFAKE_MUTEX(push_pop_);
+// };
+//
+//
+// Example: Queue implementation non thread-safe but still usable if clients
+//          are synchronized somehow, it calls a method to "protect" from
+//          a "protected" method
+//
+//          In this case the macro DFAKE_SCOPED_RECURSIVE_LOCK
+//          has to be used, it checks that if a thread is inside the push/pop
+//          then noone else is still inside the pop/push
+//
+// class NonThreadSafeQueue {
+//  public:
+//   void push(int) {
+//     DFAKE_SCOPED_LOCK(push_pop_);
+//     ...
+//   }
+//   int pop() {
+//     DFAKE_SCOPED_RECURSIVE_LOCK(push_pop_);
+//     bar();
+//     ...
+//   }
+//   void bar() { DFAKE_SCOPED_RECURSIVE_LOCK(push_pop_); ... }
+//   ...
+//  private:
+//   DFAKE_MUTEX(push_pop_);
+// };
+//
+//
+// Example: Queue implementation not usable even if clients are synchronized,
+//          so only one thread in the class life cycle can use the two members
+//          push/pop.
+//
+//          In this case the macro DFAKE_SCOPED_LOCK_THREAD_LOCKED pins the
+//          specified
+//          critical section the first time a thread enters push or pop, from
+//          that time on only that thread is allowed to execute push or pop.
+//
+// class NonThreadSafeQueue {
+//  public:
+//   ...
+//   void push(int) { DFAKE_SCOPED_LOCK_THREAD_LOCKED(push_pop_); ... }
+//   int pop() { DFAKE_SCOPED_LOCK_THREAD_LOCKED(push_pop_); ... }
+//   ...
+//  private:
+//   DFAKE_MUTEX(push_pop_);
+// };
+//
+//
+// Example: Class that has to be contructed/destroyed on same thread, it has
+//          a "shareable" method (with external synchronization) and a not
+//          shareable method (even with external synchronization).
+//
+//          In this case 3 Critical sections have to be defined
+//
+// class ExoticClass {
+//  public:
+//   ExoticClass() { DFAKE_SCOPED_LOCK_THREAD_LOCKED(ctor_dtor_); ... }
+//   ~ExoticClass() { DFAKE_SCOPED_LOCK_THREAD_LOCKED(ctor_dtor_); ... }
+//
+//   void Shareable() { DFAKE_SCOPED_LOCK(shareable_section_); ... }
+//   void NotShareable() { DFAKE_SCOPED_LOCK_THREAD_LOCKED(ctor_dtor_); ... }
+//   ...
+//  private:
+//   DFAKE_MUTEX(ctor_dtor_);
+//   DFAKE_MUTEX(shareable_section_);
+// };
+
+
+#if !defined(NDEBUG)
+
+// Defines a class member that acts like a mutex. It is used only as a
+// verification tool.
+#define DFAKE_MUTEX(obj) \
+     mutable base::ThreadCollisionWarner obj
+// Asserts the call is never called simultaneously in two threads. Used at
+// member function scope.
+#define DFAKE_SCOPED_LOCK(obj) \
+     base::ThreadCollisionWarner::ScopedCheck s_check_##obj(&obj)
+// Asserts the call is never called simultaneously in two threads. Used at
+// member function scope. Same as DFAKE_SCOPED_LOCK but allows recursive locks.
+#define DFAKE_SCOPED_RECURSIVE_LOCK(obj) \
+     base::ThreadCollisionWarner::ScopedRecursiveCheck sr_check_##obj(&obj)
+// Asserts the code is always executed in the same thread.
+#define DFAKE_SCOPED_LOCK_THREAD_LOCKED(obj) \
+     base::ThreadCollisionWarner::Check check_##obj(&obj)
+
+#else
+
+#define DFAKE_MUTEX(obj) typedef void InternalFakeMutexType##obj
+#define DFAKE_SCOPED_LOCK(obj) ((void)0)
+#define DFAKE_SCOPED_RECURSIVE_LOCK(obj) ((void)0)
+#define DFAKE_SCOPED_LOCK_THREAD_LOCKED(obj) ((void)0)
+
+#endif
+
+namespace base {
+
+// The class ThreadCollisionWarner uses an Asserter to notify the collision
+// AsserterBase is the interfaces and DCheckAsserter is the default asserter
+// used. During the unit tests is used another class that doesn't "DCHECK"
+// in case of collision (check thread_collision_warner_unittests.cc)
+struct BASE_EXPORT AsserterBase {
+  virtual ~AsserterBase() {}
+  virtual void warn() = 0;
+};
+
+struct BASE_EXPORT DCheckAsserter : public AsserterBase {
+  virtual ~DCheckAsserter() {}
+  virtual void warn() OVERRIDE;
+};
+
+class BASE_EXPORT ThreadCollisionWarner {
+ public:
+  // The parameter asserter is there only for test purpose
+  explicit ThreadCollisionWarner(AsserterBase* asserter = new DCheckAsserter())
+      : valid_thread_id_(0),
+        counter_(0),
+        asserter_(asserter) {}
+
+  ~ThreadCollisionWarner() {
+    delete asserter_;
+  }
+
+  // This class is meant to be used through the macro
+  // DFAKE_SCOPED_LOCK_THREAD_LOCKED
+  // it doesn't leave the critical section, as opposed to ScopedCheck,
+  // because the critical section being pinned is allowed to be used only
+  // from one thread
+  class BASE_EXPORT Check {
+   public:
+    explicit Check(ThreadCollisionWarner* warner)
+        : warner_(warner) {
+      warner_->EnterSelf();
+    }
+
+    ~Check() {}
+
+   private:
+    ThreadCollisionWarner* warner_;
+
+    DISALLOW_COPY_AND_ASSIGN(Check);
+  };
+
+  // This class is meant to be used through the macro
+  // DFAKE_SCOPED_LOCK
+  class BASE_EXPORT ScopedCheck {
+   public:
+    explicit ScopedCheck(ThreadCollisionWarner* warner)
+        : warner_(warner) {
+      warner_->Enter();
+    }
+
+    ~ScopedCheck() {
+      warner_->Leave();
+    }
+
+   private:
+    ThreadCollisionWarner* warner_;
+
+    DISALLOW_COPY_AND_ASSIGN(ScopedCheck);
+  };
+
+  // This class is meant to be used through the macro
+  // DFAKE_SCOPED_RECURSIVE_LOCK
+  class BASE_EXPORT ScopedRecursiveCheck {
+   public:
+    explicit ScopedRecursiveCheck(ThreadCollisionWarner* warner)
+        : warner_(warner) {
+      warner_->EnterSelf();
+    }
+
+    ~ScopedRecursiveCheck() {
+      warner_->Leave();
+    }
+
+   private:
+    ThreadCollisionWarner* warner_;
+
+    DISALLOW_COPY_AND_ASSIGN(ScopedRecursiveCheck);
+  };
+
+ private:
+  // This method stores the current thread identifier and does a DCHECK
+  // if a another thread has already done it, it is safe if same thread
+  // calls this multiple time (recursion allowed).
+  void EnterSelf();
+
+  // Same as EnterSelf but recursion is not allowed.
+  void Enter();
+
+  // Removes the thread_id stored in order to allow other threads to
+  // call EnterSelf or Enter.
+  void Leave();
+
+  // This stores the thread id that is inside the critical section, if the
+  // value is 0 then no thread is inside.
+  volatile subtle::Atomic32 valid_thread_id_;
+
+  // Counter to trace how many time a critical section was "pinned"
+  // (when allowed) in order to unpin it when counter_ reaches 0.
+  volatile subtle::Atomic32 counter_;
+
+  // Here only for class unit tests purpose, during the test I need to not
+  // DCHECK but notify the collision with something else.
+  AsserterBase* asserter_;
+
+  DISALLOW_COPY_AND_ASSIGN(ThreadCollisionWarner);
+};
+
+}  // namespace base
+
+#endif  // BASE_THREADING_THREAD_COLLISION_WARNER_H_
diff --git a/chromium/base/threading/thread_collision_warner_unittest.cc b/chromium/base/threading/thread_collision_warner_unittest.cc
new file mode 100644
index 00000000000..48710a7f3cc
--- /dev/null
+++ b/chromium/base/threading/thread_collision_warner_unittest.cc
@@ -0,0 +1,385 @@
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "base/compiler_specific.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/synchronization/lock.h"
+#include "base/threading/platform_thread.h"
+#include "base/threading/simple_thread.h"
+#include "base/threading/thread_collision_warner.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+// '' : local class member function does not have a body
+MSVC_PUSH_DISABLE_WARNING(4822)
+
+
+#if defined(NDEBUG)
+
+// Would cause a memory leak otherwise.
+#undef DFAKE_MUTEX
+#define DFAKE_MUTEX(obj) scoped_ptr<base::AsserterBase> obj
+
+// In Release, we expect the AsserterBase::warn() to not happen.
+#define EXPECT_NDEBUG_FALSE_DEBUG_TRUE EXPECT_FALSE
+
+#else
+
+// In Debug, we expect the AsserterBase::warn() to happen.
+#define EXPECT_NDEBUG_FALSE_DEBUG_TRUE EXPECT_TRUE
+
+#endif
+
+
+namespace {
+
+// This is the asserter used with ThreadCollisionWarner instead of the default
+// DCheckAsserter. The method fail_state is used to know if a collision took
+// place.
+class AssertReporter : public base::AsserterBase {
+ public:
+  AssertReporter()
+      : failed_(false) {}
+
+  virtual void warn() OVERRIDE {
+    failed_ = true;
+  }
+
+  virtual ~AssertReporter() {}
+
+  bool fail_state() const { return failed_; }
+  void reset() { failed_ = false; }
+
+ private:
+  bool failed_;
+};
+
+}  // namespace
+
+TEST(ThreadCollisionTest, BookCriticalSection) {
+  AssertReporter* local_reporter = new AssertReporter();
+
+  base::ThreadCollisionWarner warner(local_reporter);
+  EXPECT_FALSE(local_reporter->fail_state());
+
+  {  // Pin section.
+    DFAKE_SCOPED_LOCK_THREAD_LOCKED(warner);
+    EXPECT_FALSE(local_reporter->fail_state());
+    {  // Pin section.
+      DFAKE_SCOPED_LOCK_THREAD_LOCKED(warner);
+      EXPECT_FALSE(local_reporter->fail_state());
+    }
+  }
+}
+
+TEST(ThreadCollisionTest, ScopedRecursiveBookCriticalSection) {
+  AssertReporter* local_reporter = new AssertReporter();
+
+  base::ThreadCollisionWarner warner(local_reporter);
+  EXPECT_FALSE(local_reporter->fail_state());
+
+  {  // Pin section.
+    DFAKE_SCOPED_RECURSIVE_LOCK(warner);
+    EXPECT_FALSE(local_reporter->fail_state());
+    {  // Pin section again (allowed by DFAKE_SCOPED_RECURSIVE_LOCK)
+      DFAKE_SCOPED_RECURSIVE_LOCK(warner);
+      EXPECT_FALSE(local_reporter->fail_state());
+    }  // Unpin section.
+  }  // Unpin section.
+
+  // Check that section is not pinned
+  {  // Pin section.
+    DFAKE_SCOPED_LOCK(warner);
+    EXPECT_FALSE(local_reporter->fail_state());
+  }  // Unpin section.
+}
+
+TEST(ThreadCollisionTest, ScopedBookCriticalSection) {
+  AssertReporter* local_reporter = new AssertReporter();
+
+  base::ThreadCollisionWarner warner(local_reporter);
+  EXPECT_FALSE(local_reporter->fail_state());
+
+  {  // Pin section.
+    DFAKE_SCOPED_LOCK(warner);
+    EXPECT_FALSE(local_reporter->fail_state());
+  }  // Unpin section.
+
+  {  // Pin section.
+    DFAKE_SCOPED_LOCK(warner);
+    EXPECT_FALSE(local_reporter->fail_state());
+    {
+      // Pin section again (not allowed by DFAKE_SCOPED_LOCK)
+      DFAKE_SCOPED_LOCK(warner);
+      EXPECT_NDEBUG_FALSE_DEBUG_TRUE(local_reporter->fail_state());
+      // Reset the status of warner for further tests.
+      local_reporter->reset();
+    }  // Unpin section.
+  }  // Unpin section.
+
+  {
+    // Pin section.
+    DFAKE_SCOPED_LOCK(warner);
+    EXPECT_FALSE(local_reporter->fail_state());
+  }  // Unpin section.
+}
+
+TEST(ThreadCollisionTest, MTBookCriticalSectionTest) {
+  class NonThreadSafeQueue {
+   public:
+    explicit NonThreadSafeQueue(base::AsserterBase* asserter)
+        : push_pop_(asserter) {
+    }
+
+    void push(int value) {
+      DFAKE_SCOPED_LOCK_THREAD_LOCKED(push_pop_);
+    }
+
+    int pop() {
+      DFAKE_SCOPED_LOCK_THREAD_LOCKED(push_pop_);
+      return 0;
+    }
+
+   private:
+    DFAKE_MUTEX(push_pop_);
+
+    DISALLOW_COPY_AND_ASSIGN(NonThreadSafeQueue);
+  };
+
+  class QueueUser : public base::DelegateSimpleThread::Delegate {
+   public:
+    explicit QueueUser(NonThreadSafeQueue& queue)
+        : queue_(queue) {}
+
+    virtual void Run() OVERRIDE {
+      queue_.push(0);
+      queue_.pop();
+    }
+
+   private:
+    NonThreadSafeQueue& queue_;
+  };
+
+  AssertReporter* local_reporter = new AssertReporter();
+
+  NonThreadSafeQueue queue(local_reporter);
+
+  QueueUser queue_user_a(queue);
+  QueueUser queue_user_b(queue);
+
+  base::DelegateSimpleThread thread_a(&queue_user_a, "queue_user_thread_a");
+  base::DelegateSimpleThread thread_b(&queue_user_b, "queue_user_thread_b");
+
+  thread_a.Start();
+  thread_b.Start();
+
+  thread_a.Join();
+  thread_b.Join();
+
+  EXPECT_NDEBUG_FALSE_DEBUG_TRUE(local_reporter->fail_state());
+}
+
+TEST(ThreadCollisionTest, MTScopedBookCriticalSectionTest) {
+  // Queue with a 5 seconds push execution time, hopefuly the two used threads
+  // in the test will enter the push at same time.
+  class NonThreadSafeQueue {
+   public:
+    explicit NonThreadSafeQueue(base::AsserterBase* asserter)
+        : push_pop_(asserter) {
+    }
+
+    void push(int value) {
+      DFAKE_SCOPED_LOCK(push_pop_);
+      base::PlatformThread::Sleep(base::TimeDelta::FromSeconds(5));
+    }
+
+    int pop() {
+      DFAKE_SCOPED_LOCK(push_pop_);
+      return 0;
+    }
+
+   private:
+    DFAKE_MUTEX(push_pop_);
+
+    DISALLOW_COPY_AND_ASSIGN(NonThreadSafeQueue);
+  };
+
+  class QueueUser : public base::DelegateSimpleThread::Delegate {
+   public:
+    explicit QueueUser(NonThreadSafeQueue& queue)
+        : queue_(queue) {}
+
+    virtual void Run() OVERRIDE {
+      queue_.push(0);
+      queue_.pop();
+    }
+
+   private:
+    NonThreadSafeQueue& queue_;
+  };
+
+  AssertReporter* local_reporter = new AssertReporter();
+
+  NonThreadSafeQueue queue(local_reporter);
+
+  QueueUser queue_user_a(queue);
+  QueueUser queue_user_b(queue);
+
+  base::DelegateSimpleThread thread_a(&queue_user_a, "queue_user_thread_a");
+  base::DelegateSimpleThread thread_b(&queue_user_b, "queue_user_thread_b");
+
+  thread_a.Start();
+  thread_b.Start();
+
+  thread_a.Join();
+  thread_b.Join();
+
+  EXPECT_NDEBUG_FALSE_DEBUG_TRUE(local_reporter->fail_state());
+}
+
+TEST(ThreadCollisionTest, MTSynchedScopedBookCriticalSectionTest) {
+  // Queue with a 2 seconds push execution time, hopefuly the two used threads
+  // in the test will enter the push at same time.
+  class NonThreadSafeQueue {
+   public:
+    explicit NonThreadSafeQueue(base::AsserterBase* asserter)
+        : push_pop_(asserter) {
+    }
+
+    void push(int value) {
+      DFAKE_SCOPED_LOCK(push_pop_);
+      base::PlatformThread::Sleep(base::TimeDelta::FromSeconds(2));
+    }
+
+    int pop() {
+      DFAKE_SCOPED_LOCK(push_pop_);
+      return 0;
+    }
+
+   private:
+    DFAKE_MUTEX(push_pop_);
+
+    DISALLOW_COPY_AND_ASSIGN(NonThreadSafeQueue);
+  };
+
+  // This time the QueueUser class protects the non thread safe queue with
+  // a lock.
+  class QueueUser : public base::DelegateSimpleThread::Delegate {
+   public:
+    QueueUser(NonThreadSafeQueue& queue, base::Lock& lock)
+        : queue_(queue),
+          lock_(lock) {}
+
+    virtual void Run() OVERRIDE {
+      {
+        base::AutoLock auto_lock(lock_);
+        queue_.push(0);
+      }
+      {
+        base::AutoLock auto_lock(lock_);
+        queue_.pop();
+      }
+    }
+   private:
+    NonThreadSafeQueue& queue_;
+    base::Lock& lock_;
+  };
+
+  AssertReporter* local_reporter = new AssertReporter();
+
+  NonThreadSafeQueue queue(local_reporter);
+
+  base::Lock lock;
+
+  QueueUser queue_user_a(queue, lock);
+  QueueUser queue_user_b(queue, lock);
+
+  base::DelegateSimpleThread thread_a(&queue_user_a, "queue_user_thread_a");
+  base::DelegateSimpleThread thread_b(&queue_user_b, "queue_user_thread_b");
+
+  thread_a.Start();
+  thread_b.Start();
+
+  thread_a.Join();
+  thread_b.Join();
+
+  EXPECT_FALSE(local_reporter->fail_state());
+}
+
+TEST(ThreadCollisionTest, MTSynchedScopedRecursiveBookCriticalSectionTest) {
+  // Queue with a 2 seconds push execution time, hopefuly the two used threads
+  // in the test will enter the push at same time.
+  class NonThreadSafeQueue {
+   public:
+    explicit NonThreadSafeQueue(base::AsserterBase* asserter)
+        : push_pop_(asserter) {
+    }
+
+    void push(int) {
+      DFAKE_SCOPED_RECURSIVE_LOCK(push_pop_);
+      bar();
+      base::PlatformThread::Sleep(base::TimeDelta::FromSeconds(2));
+    }
+
+    int pop() {
+      DFAKE_SCOPED_RECURSIVE_LOCK(push_pop_);
+      return 0;
+    }
+
+    void bar() {
+      DFAKE_SCOPED_RECURSIVE_LOCK(push_pop_);
+    }
+
+   private:
+    DFAKE_MUTEX(push_pop_);
+
+    DISALLOW_COPY_AND_ASSIGN(NonThreadSafeQueue);
+  };
+
+  // This time the QueueUser class protects the non thread safe queue with
+  // a lock.
+  class QueueUser : public base::DelegateSimpleThread::Delegate {
+   public:
+    QueueUser(NonThreadSafeQueue& queue, base::Lock& lock)
+        : queue_(queue),
+          lock_(lock) {}
+
+    virtual void Run() OVERRIDE {
+      {
+        base::AutoLock auto_lock(lock_);
+        queue_.push(0);
+      }
+      {
+        base::AutoLock auto_lock(lock_);
+        queue_.bar();
+      }
+      {
+        base::AutoLock auto_lock(lock_);
+        queue_.pop();
+      }
+    }
+   private:
+    NonThreadSafeQueue& queue_;
+    base::Lock& lock_;
+  };
+
+  AssertReporter* local_reporter = new AssertReporter();
+
+  NonThreadSafeQueue queue(local_reporter);
+
+  base::Lock lock;
+
+  QueueUser queue_user_a(queue, lock);
+  QueueUser queue_user_b(queue, lock);
+
+  base::DelegateSimpleThread thread_a(&queue_user_a, "queue_user_thread_a");
+  base::DelegateSimpleThread thread_b(&queue_user_b, "queue_user_thread_b");
+
+  thread_a.Start();
+  thread_b.Start();
+
+  thread_a.Join();
+  thread_b.Join();
+
+  EXPECT_FALSE(local_reporter->fail_state());
+}
diff --git a/chromium/base/threading/thread_id_name_manager.cc b/chromium/base/threading/thread_id_name_manager.cc
new file mode 100644
index 00000000000..ef08548f2ed
--- /dev/null
+++ b/chromium/base/threading/thread_id_name_manager.cc
@@ -0,0 +1,112 @@
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "base/threading/thread_id_name_manager.h"
+
+#include <stdlib.h>
+#include <string.h>
+
+#include "base/logging.h"
+#include "base/memory/singleton.h"
+#include "base/strings/string_util.h"
+
+namespace base {
+namespace {
+
+static const char kDefaultName[] = "";
+static std::string* g_default_name;
+
+}
+
+ThreadIdNameManager::ThreadIdNameManager()
+    : main_process_id_(kInvalidThreadId) {
+  g_default_name = new std::string(kDefaultName);
+
+  AutoLock locked(lock_);
+  name_to_interned_name_[kDefaultName] = g_default_name;
+}
+
+ThreadIdNameManager::~ThreadIdNameManager() {
+}
+
+ThreadIdNameManager* ThreadIdNameManager::GetInstance() {
+  return Singleton<ThreadIdNameManager,
+      LeakySingletonTraits<ThreadIdNameManager> >::get();
+}
+
+const char* ThreadIdNameManager::GetDefaultInternedString() {
+  return g_default_name->c_str();
+}
+
+void ThreadIdNameManager::RegisterThread(PlatformThreadHandle::Handle handle,
+                                         PlatformThreadId id) {
+  AutoLock locked(lock_);
+  thread_id_to_handle_[id] = handle;
+  thread_handle_to_interned_name_[handle] =
+      name_to_interned_name_[kDefaultName];
+}
+
+void ThreadIdNameManager::SetName(PlatformThreadId id, const char* name) {
+  std::string str_name(name);
+
+  AutoLock locked(lock_);
+  NameToInternedNameMap::iterator iter = name_to_interned_name_.find(str_name);
+  std::string* leaked_str = NULL;
+  if (iter != name_to_interned_name_.end()) {
+    leaked_str = iter->second;
+  } else {
+    leaked_str = new std::string(str_name);
+    name_to_interned_name_[str_name] = leaked_str;
+  }
+
+  ThreadIdToHandleMap::iterator id_to_handle_iter =
+      thread_id_to_handle_.find(id);
+
+  // The main thread of a process will not be created as a Thread object which
+  // means there is no PlatformThreadHandler registered.
+  if (id_to_handle_iter == thread_id_to_handle_.end()) {
+    main_process_name_ = leaked_str;
+    main_process_id_ = id;
+    return;
+  }
+  thread_handle_to_interned_name_[id_to_handle_iter->second] = leaked_str;
+}
+
+const char* ThreadIdNameManager::GetName(PlatformThreadId id) {
+  AutoLock locked(lock_);
+
+  if (id == main_process_id_)
+    return main_process_name_->c_str();
+
+  ThreadIdToHandleMap::iterator id_to_handle_iter =
+      thread_id_to_handle_.find(id);
+  if (id_to_handle_iter == thread_id_to_handle_.end())
+    return name_to_interned_name_[kDefaultName]->c_str();
+
+  ThreadHandleToInternedNameMap::iterator handle_to_name_iter =
+      thread_handle_to_interned_name_.find(id_to_handle_iter->second);
+  return handle_to_name_iter->second->c_str();
+}
+
+void ThreadIdNameManager::RemoveName(PlatformThreadHandle::Handle handle,
+                                     PlatformThreadId id) {
+  AutoLock locked(lock_);
+  ThreadHandleToInternedNameMap::iterator handle_to_name_iter =
+      thread_handle_to_interned_name_.find(handle);
+
+  DCHECK(handle_to_name_iter != thread_handle_to_interned_name_.end());
+  thread_handle_to_interned_name_.erase(handle_to_name_iter);
+
+  ThreadIdToHandleMap::iterator id_to_handle_iter =
+      thread_id_to_handle_.find(id);
+  DCHECK((id_to_handle_iter!= thread_id_to_handle_.end()));
+  // The given |id| may have been re-used by the system. Make sure the
+  // mapping points to the provided |handle| before removal.
+  if (id_to_handle_iter->second != handle)
+    return;
+
+  thread_id_to_handle_.erase(id_to_handle_iter);
+}
+
+}  // namespace base
diff --git a/chromium/base/threading/thread_id_name_manager.h b/chromium/base/threading/thread_id_name_manager.h
new file mode 100644
index 00000000000..0ea59df6572
--- /dev/null
+++ b/chromium/base/threading/thread_id_name_manager.h
@@ -0,0 +1,67 @@
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef BASE_THREADING_THREAD_ID_NAME_MANAGER_H_
+#define BASE_THREADING_THREAD_ID_NAME_MANAGER_H_
+
+#include <map>
+#include <string>
+
+#include "base/base_export.h"
+#include "base/basictypes.h"
+#include "base/synchronization/lock.h"
+#include "base/threading/platform_thread.h"
+
+template <typename T> struct DefaultSingletonTraits;
+
+namespace base {
+
+class BASE_EXPORT ThreadIdNameManager {
+ public:
+  static ThreadIdNameManager* GetInstance();
+
+  static const char* GetDefaultInternedString();
+
+  // Register the mapping between a thread |id| and |handle|.
+  void RegisterThread(PlatformThreadHandle::Handle handle, PlatformThreadId id);
+
+  // Set the name for the given id.
+  void SetName(PlatformThreadId id, const char* name);
+
+  // Get the name for the given id.
+  const char* GetName(PlatformThreadId id);
+
+  // Remove the name for the given id.
+  void RemoveName(PlatformThreadHandle::Handle handle, PlatformThreadId id);
+
+ private:
+  friend struct DefaultSingletonTraits<ThreadIdNameManager>;
+
+  typedef std::map<PlatformThreadId, PlatformThreadHandle::Handle>
+      ThreadIdToHandleMap;
+  typedef std::map<PlatformThreadHandle::Handle, std::string*>
+      ThreadHandleToInternedNameMap;
+  typedef std::map<std::string, std::string*> NameToInternedNameMap;
+
+  ThreadIdNameManager();
+  ~ThreadIdNameManager();
+
+  // lock_ protects the name_to_interned_name_, thread_id_to_handle_ and
+  // thread_handle_to_interned_name_ maps.
+  Lock lock_;
+
+  NameToInternedNameMap name_to_interned_name_;
+  ThreadIdToHandleMap thread_id_to_handle_;
+  ThreadHandleToInternedNameMap thread_handle_to_interned_name_;
+
+  // Treat the main process specially as there is no PlatformThreadHandle.
+  std::string* main_process_name_;
+  PlatformThreadId main_process_id_;
+
+  DISALLOW_COPY_AND_ASSIGN(ThreadIdNameManager);
+};
+
+}  // namespace base
+
+#endif  // BASE_THREADING_THREAD_ID_NAME_MANAGER_H_
diff --git a/chromium/base/threading/thread_id_name_manager_unittest.cc b/chromium/base/threading/thread_id_name_manager_unittest.cc
new file mode 100644
index 00000000000..37773018a0e
--- /dev/null
+++ b/chromium/base/threading/thread_id_name_manager_unittest.cc
@@ -0,0 +1,93 @@
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "base/threading/thread_id_name_manager.h"
+
+#include "base/threading/platform_thread.h"
+#include "base/threading/thread.h"
+#include "testing/gtest/include/gtest/gtest.h"
+#include "testing/platform_test.h"
+
+typedef PlatformTest ThreadIdNameManagerTest;
+
+namespace {
+
+static const char* kAThread = "a thread";
+static const char* kBThread = "b thread";
+
+TEST_F(ThreadIdNameManagerTest, AddThreads) {
+  base::ThreadIdNameManager* manager = base::ThreadIdNameManager::GetInstance();
+  base::Thread thread_a(kAThread);
+  base::Thread thread_b(kBThread);
+
+  thread_a.Start();
+  thread_b.Start();
+
+  EXPECT_STREQ(kAThread, manager->GetName(thread_a.thread_id()));
+  EXPECT_STREQ(kBThread, manager->GetName(thread_b.thread_id()));
+
+  thread_b.Stop();
+  thread_a.Stop();
+}
+
+TEST_F(ThreadIdNameManagerTest, RemoveThreads) {
+  base::ThreadIdNameManager* manager = base::ThreadIdNameManager::GetInstance();
+  base::Thread thread_a(kAThread);
+
+  thread_a.Start();
+  {
+    base::Thread thread_b(kBThread);
+    thread_b.Start();
+    thread_b.Stop();
+  }
+  EXPECT_STREQ(kAThread, manager->GetName(thread_a.thread_id()));
+
+  thread_a.Stop();
+  EXPECT_STREQ("", manager->GetName(thread_a.thread_id()));
+}
+
+TEST_F(ThreadIdNameManagerTest, RestartThread) {
+  base::ThreadIdNameManager* manager = base::ThreadIdNameManager::GetInstance();
+  base::Thread thread_a(kAThread);
+
+  thread_a.Start();
+  base::PlatformThreadId a_id = thread_a.thread_id();
+  EXPECT_STREQ(kAThread, manager->GetName(a_id));
+  thread_a.Stop();
+
+  thread_a.Start();
+  EXPECT_STREQ("", manager->GetName(a_id));
+  EXPECT_STREQ(kAThread, manager->GetName(thread_a.thread_id()));
+  thread_a.Stop();
+}
+
+TEST_F(ThreadIdNameManagerTest, ThreadNameInterning) {
+  base::ThreadIdNameManager* manager = base::ThreadIdNameManager::GetInstance();
+
+  base::PlatformThreadId a_id = base::PlatformThread::CurrentId();
+  base::PlatformThread::SetName("First Name");
+  std::string version = manager->GetName(a_id);
+
+  base::PlatformThread::SetName("New name");
+  EXPECT_NE(version, manager->GetName(a_id));
+  base::PlatformThread::SetName("");
+}
+
+TEST_F(ThreadIdNameManagerTest, ResettingNameKeepsCorrectInternedValue) {
+  base::ThreadIdNameManager* manager = base::ThreadIdNameManager::GetInstance();
+
+  base::PlatformThreadId a_id = base::PlatformThread::CurrentId();
+  base::PlatformThread::SetName("Test Name");
+  std::string version = manager->GetName(a_id);
+
+  base::PlatformThread::SetName("New name");
+  EXPECT_NE(version, manager->GetName(a_id));
+
+  base::PlatformThread::SetName("Test Name");
+  EXPECT_EQ(version, manager->GetName(a_id));
+
+  base::PlatformThread::SetName("");
+}
+
+}  // namespace
diff --git a/chromium/base/threading/thread_local.h b/chromium/base/threading/thread_local.h
new file mode 100644
index 00000000000..6561420758c
--- /dev/null
+++ b/chromium/base/threading/thread_local.h
@@ -0,0 +1,128 @@
+// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// WARNING: Thread local storage is a bit tricky to get right.  Please make
+// sure that this is really the proper solution for what you're trying to
+// achieve.  Don't prematurely optimize, most likely you can just use a Lock.
+//
+// These classes implement a wrapper around the platform's TLS storage
+// mechanism.  On construction, they will allocate a TLS slot, and free the
+// TLS slot on destruction.  No memory management (creation or destruction) is
+// handled.  This means for uses of ThreadLocalPointer, you must correctly
+// manage the memory yourself, these classes will not destroy the pointer for
+// you.  There are no at-thread-exit actions taken by these classes.
+//
+// ThreadLocalPointer<Type> wraps a Type*.  It performs no creation or
+// destruction, so memory management must be handled elsewhere.  The first call
+// to Get() on a thread will return NULL.  You can update the pointer with a
+// call to Set().
+//
+// ThreadLocalBoolean wraps a bool.  It will default to false if it has never
+// been set otherwise with Set().
+//
+// Thread Safety:  An instance of ThreadLocalStorage is completely thread safe
+// once it has been created.  If you want to dynamically create an instance,
+// you must of course properly deal with safety and race conditions.  This
+// means a function-level static initializer is generally inappropiate.
+//
+// Example usage:
+//   // My class is logically attached to a single thread.  We cache a pointer
+//   // on the thread it was created on, so we can implement current().
+//   MyClass::MyClass() {
+//     DCHECK(Singleton<ThreadLocalPointer<MyClass> >::get()->Get() == NULL);
+//     Singleton<ThreadLocalPointer<MyClass> >::get()->Set(this);
+//   }
+//
+//   MyClass::~MyClass() {
+//     DCHECK(Singleton<ThreadLocalPointer<MyClass> >::get()->Get() != NULL);
+//     Singleton<ThreadLocalPointer<MyClass> >::get()->Set(NULL);
+//   }
+//
+//   // Return the current MyClass associated with the calling thread, can be
+//   // NULL if there isn't a MyClass associated.
+//   MyClass* MyClass::current() {
+//     return Singleton<ThreadLocalPointer<MyClass> >::get()->Get();
+//   }
+
+#ifndef BASE_THREADING_THREAD_LOCAL_H_
+#define BASE_THREADING_THREAD_LOCAL_H_
+
+#include "base/base_export.h"
+#include "base/basictypes.h"
+
+#if defined(OS_POSIX)
+#include <pthread.h>
+#endif
+
+namespace base {
+
+namespace internal {
+
+// Helper functions that abstract the cross-platform APIs.  Do not use directly.
+struct BASE_EXPORT ThreadLocalPlatform {
+#if defined(OS_WIN)
+  typedef unsigned long SlotType;
+#elif defined(OS_POSIX)
+  typedef pthread_key_t SlotType;
+#endif
+
+  static void AllocateSlot(SlotType& slot);
+  static void FreeSlot(SlotType& slot);
+  static void* GetValueFromSlot(SlotType& slot);
+  static void SetValueInSlot(SlotType& slot, void* value);
+};
+
+}  // namespace internal
+
+template <typename Type>
+class ThreadLocalPointer {
+ public:
+  ThreadLocalPointer() : slot_() {
+    internal::ThreadLocalPlatform::AllocateSlot(slot_);
+  }
+
+  ~ThreadLocalPointer() {
+    internal::ThreadLocalPlatform::FreeSlot(slot_);
+  }
+
+  Type* Get() {
+    return static_cast<Type*>(
+        internal::ThreadLocalPlatform::GetValueFromSlot(slot_));
+  }
+
+  void Set(Type* ptr) {
+    internal::ThreadLocalPlatform::SetValueInSlot(
+        slot_, const_cast<void*>(static_cast<const void*>(ptr)));
+  }
+
+ private:
+  typedef internal::ThreadLocalPlatform::SlotType SlotType;
+
+  SlotType slot_;
+
+  DISALLOW_COPY_AND_ASSIGN(ThreadLocalPointer<Type>);
+};
+
+class ThreadLocalBoolean {
+ public:
+  ThreadLocalBoolean() { }
+  ~ThreadLocalBoolean() { }
+
+  bool Get() {
+    return tlp_.Get() != NULL;
+  }
+
+  void Set(bool val) {
+    tlp_.Set(val ? this : NULL);
+  }
+
+ private:
+  ThreadLocalPointer<void> tlp_;
+
+  DISALLOW_COPY_AND_ASSIGN(ThreadLocalBoolean);
+};
+
+}  // namespace base
+
+#endif  // BASE_THREADING_THREAD_LOCAL_H_
diff --git a/chromium/base/threading/thread_local_posix.cc b/chromium/base/threading/thread_local_posix.cc
new file mode 100644
index 00000000000..49510064e75
--- /dev/null
+++ b/chromium/base/threading/thread_local_posix.cc
@@ -0,0 +1,40 @@
+// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "base/threading/thread_local.h"
+
+#include <pthread.h>
+
+#include "base/logging.h"
+
+namespace base {
+
+namespace internal {
+
+// static
+void ThreadLocalPlatform::AllocateSlot(SlotType& slot) {
+  int error = pthread_key_create(&slot, NULL);
+  CHECK_EQ(error, 0);
+}
+
+// static
+void ThreadLocalPlatform::FreeSlot(SlotType& slot) {
+  int error = pthread_key_delete(slot);
+  DCHECK_EQ(0, error);
+}
+
+// static
+void* ThreadLocalPlatform::GetValueFromSlot(SlotType& slot) {
+  return pthread_getspecific(slot);
+}
+
+// static
+void ThreadLocalPlatform::SetValueInSlot(SlotType& slot, void* value) {
+  int error = pthread_setspecific(slot, value);
+  DCHECK_EQ(error, 0);
+}
+
+}  // namespace internal
+
+}  // namespace base
diff --git a/chromium/base/threading/thread_local_storage.h b/chromium/base/threading/thread_local_storage.h
new file mode 100644
index 00000000000..eb5648f76c9
--- /dev/null
+++ b/chromium/base/threading/thread_local_storage.h
@@ -0,0 +1,93 @@
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef BASE_THREADING_THREAD_LOCAL_STORAGE_H_
+#define BASE_THREADING_THREAD_LOCAL_STORAGE_H_
+
+#include "base/base_export.h"
+#include "base/basictypes.h"
+
+#if defined(OS_POSIX)
+#include <pthread.h>
+#endif
+
+namespace base {
+
+// Wrapper for thread local storage.  This class doesn't do much except provide
+// an API for portability.
+class BASE_EXPORT ThreadLocalStorage {
+ public:
+
+  // Prototype for the TLS destructor function, which can be optionally used to
+  // cleanup thread local storage on thread exit.  'value' is the data that is
+  // stored in thread local storage.
+  typedef void (*TLSDestructorFunc)(void* value);
+
+  // StaticSlot uses its own struct initializer-list style static
+  // initialization, as base's LINKER_INITIALIZED requires a constructor and on
+  // some compilers (notably gcc 4.4) this still ends up needing runtime
+  // initialization.
+  #define TLS_INITIALIZER {0}
+
+  // A key representing one value stored in TLS.
+  // Initialize like
+  //   ThreadLocalStorage::StaticSlot my_slot = TLS_INITIALIZER;
+  // If you're not using a static variable, use the convenience class
+  // ThreadLocalStorage::Slot (below) instead.
+  struct BASE_EXPORT StaticSlot {
+    // Set up the TLS slot.  Called by the constructor.
+    // 'destructor' is a pointer to a function to perform per-thread cleanup of
+    // this object.  If set to NULL, no cleanup is done for this TLS slot.
+    // Returns false on error.
+    bool Initialize(TLSDestructorFunc destructor);
+
+    // Free a previously allocated TLS 'slot'.
+    // If a destructor was set for this slot, removes
+    // the destructor so that remaining threads exiting
+    // will not free data.
+    void Free();
+
+    // Get the thread-local value stored in slot 'slot'.
+    // Values are guaranteed to initially be zero.
+    void* Get() const;
+
+    // Set the thread-local value stored in slot 'slot' to
+    // value 'value'.
+    void Set(void* value);
+
+    bool initialized() const { return initialized_; }
+
+    // The internals of this struct should be considered private.
+    bool initialized_;
+#if defined(OS_WIN)
+    int slot_;
+#elif defined(OS_POSIX)
+    pthread_key_t key_;
+#endif
+
+  };
+
+  // A convenience wrapper around StaticSlot with a constructor. Can be used
+  // as a member variable.
+  class BASE_EXPORT Slot : public StaticSlot {
+   public:
+    // Calls StaticSlot::Initialize().
+    explicit Slot(TLSDestructorFunc destructor = NULL);
+
+   private:
+    using StaticSlot::initialized_;
+#if defined(OS_WIN)
+    using StaticSlot::slot_;
+#elif defined(OS_POSIX)
+    using StaticSlot::key_;
+#endif
+    DISALLOW_COPY_AND_ASSIGN(Slot);
+  };
+
+  DISALLOW_COPY_AND_ASSIGN(ThreadLocalStorage);
+};
+
+}  // namespace base
+
+#endif  // BASE_THREADING_THREAD_LOCAL_STORAGE_H_
diff --git a/chromium/base/threading/thread_local_storage_posix.cc b/chromium/base/threading/thread_local_storage_posix.cc
new file mode 100644
index 00000000000..75da5a7d8f0
--- /dev/null
+++ b/chromium/base/threading/thread_local_storage_posix.cc
@@ -0,0 +1,49 @@
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "base/threading/thread_local_storage.h"
+
+#include "base/logging.h"
+
+namespace base {
+
+ThreadLocalStorage::Slot::Slot(TLSDestructorFunc destructor) {
+  initialized_ = false;
+  key_ = 0;
+  Initialize(destructor);
+}
+
+bool ThreadLocalStorage::StaticSlot::Initialize(TLSDestructorFunc destructor) {
+  DCHECK(!initialized_);
+  int error = pthread_key_create(&key_, destructor);
+  if (error) {
+    NOTREACHED();
+    return false;
+  }
+
+  initialized_ = true;
+  return true;
+}
+
+void ThreadLocalStorage::StaticSlot::Free() {
+  DCHECK(initialized_);
+  int error = pthread_key_delete(key_);
+  if (error)
+    NOTREACHED();
+  initialized_ = false;
+}
+
+void* ThreadLocalStorage::StaticSlot::Get() const {
+  DCHECK(initialized_);
+  return pthread_getspecific(key_);
+}
+
+void ThreadLocalStorage::StaticSlot::Set(void* value) {
+  DCHECK(initialized_);
+  int error = pthread_setspecific(key_, value);
+  if (error)
+    NOTREACHED();
+}
+
+}  // namespace base
diff --git a/chromium/base/threading/thread_local_storage_unittest.cc b/chromium/base/threading/thread_local_storage_unittest.cc
new file mode 100644
index 00000000000..e295c89426d
--- /dev/null
+++ b/chromium/base/threading/thread_local_storage_unittest.cc
@@ -0,0 +1,124 @@
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#if defined(OS_WIN)
+#include <windows.h>
+#include <process.h>
+#endif
+
+#include "base/threading/simple_thread.h"
+#include "base/threading/thread_local_storage.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+#if defined(OS_WIN)
+// Ignore warnings about ptr->int conversions that we use when
+// storing ints into ThreadLocalStorage.
+#pragma warning(disable : 4311 4312)
+#endif
+
+namespace base {
+
+namespace {
+
+const int kInitialTlsValue = 0x5555;
+const int kFinalTlsValue = 0x7777;
+// How many times must a destructor be called before we really are done.
+const int kNumberDestructorCallRepetitions = 3;
+
+static ThreadLocalStorage::StaticSlot tls_slot = TLS_INITIALIZER;
+
+class ThreadLocalStorageRunner : public DelegateSimpleThread::Delegate {
+ public:
+  explicit ThreadLocalStorageRunner(int* tls_value_ptr)
+      : tls_value_ptr_(tls_value_ptr) {}
+
+  virtual ~ThreadLocalStorageRunner() {}
+
+  virtual void Run() OVERRIDE {
+    *tls_value_ptr_ = kInitialTlsValue;
+    tls_slot.Set(tls_value_ptr_);
+
+    int *ptr = static_cast<int*>(tls_slot.Get());
+    EXPECT_EQ(ptr, tls_value_ptr_);
+    EXPECT_EQ(*ptr, kInitialTlsValue);
+    *tls_value_ptr_ = 0;
+
+    ptr = static_cast<int*>(tls_slot.Get());
+    EXPECT_EQ(ptr, tls_value_ptr_);
+    EXPECT_EQ(*ptr, 0);
+
+    *ptr = kFinalTlsValue + kNumberDestructorCallRepetitions;
+  }
+
+ private:
+  int* tls_value_ptr_;
+  DISALLOW_COPY_AND_ASSIGN(ThreadLocalStorageRunner);
+};
+
+
+void ThreadLocalStorageCleanup(void *value) {
+  int *ptr = reinterpret_cast<int*>(value);
+  // Destructors should never be called with a NULL.
+  ASSERT_NE(reinterpret_cast<int*>(NULL), ptr);
+  if (*ptr == kFinalTlsValue)
+    return;  // We've been called enough times.
+  ASSERT_LT(kFinalTlsValue, *ptr);
+  ASSERT_GE(kFinalTlsValue + kNumberDestructorCallRepetitions, *ptr);
+  --*ptr;  // Move closer to our target.
+  // Tell tls that we're not done with this thread, and still need destruction.
+  tls_slot.Set(value);
+}
+
+}  // namespace
+
+TEST(ThreadLocalStorageTest, Basics) {
+  ThreadLocalStorage::Slot slot;
+  slot.Set(reinterpret_cast<void*>(123));
+  int value = reinterpret_cast<intptr_t>(slot.Get());
+  EXPECT_EQ(value, 123);
+}
+
+#if defined(THREAD_SANITIZER)
+// Do not run the test under ThreadSanitizer. Because this test iterates its
+// own TSD destructor for the maximum possible number of times, TSan can't jump
+// in after the last destructor invocation, therefore the destructor remains
+// unsynchronized with the following users of the same TSD slot. This results
+// in race reports between the destructor and functions in other tests.
+#define MAYBE_TLSDestructors DISABLED_TLSDestructors
+#else
+#define MAYBE_TLSDestructors TLSDestructors
+#endif
+TEST(ThreadLocalStorageTest, MAYBE_TLSDestructors) {
+  // Create a TLS index with a destructor.  Create a set of
+  // threads that set the TLS, while the destructor cleans it up.
+  // After the threads finish, verify that the value is cleaned up.
+  const int kNumThreads = 5;
+  int values[kNumThreads];
+  ThreadLocalStorageRunner* thread_delegates[kNumThreads];
+  DelegateSimpleThread* threads[kNumThreads];
+
+  tls_slot.Initialize(ThreadLocalStorageCleanup);
+
+  // Spawn the threads.
+  for (int index = 0; index < kNumThreads; index++) {
+    values[index] = kInitialTlsValue;
+    thread_delegates[index] = new ThreadLocalStorageRunner(&values[index]);
+    threads[index] = new DelegateSimpleThread(thread_delegates[index],
+                                              "tls thread");
+    threads[index]->Start();
+  }
+
+  // Wait for the threads to finish.
+  for (int index = 0; index < kNumThreads; index++) {
+    threads[index]->Join();
+    delete threads[index];
+    delete thread_delegates[index];
+
+    // Verify that the destructor was called and that we reset.
+    EXPECT_EQ(values[index], kFinalTlsValue);
+  }
+  tls_slot.Free();  // Stop doing callbacks to cleanup threads.
+}
+
+}  // namespace base
diff --git a/chromium/base/threading/thread_local_storage_win.cc b/chromium/base/threading/thread_local_storage_win.cc
new file mode 100644
index 00000000000..0ae3cb4c8cd
--- /dev/null
+++ b/chromium/base/threading/thread_local_storage_win.cc
@@ -0,0 +1,277 @@
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "base/threading/thread_local_storage.h"
+
+#include <windows.h>
+
+#include "base/logging.h"
+
+
+namespace {
+// In order to make TLS destructors work, we need to keep function
+// pointers to the destructor for each TLS that we allocate.
+// We make this work by allocating a single OS-level TLS, which
+// contains an array of slots for the application to use.  In
+// parallel, we also allocate an array of destructors, which we
+// keep track of and call when threads terminate.
+
+// g_native_tls_key is the one native TLS that we use.  It stores our table.
+long g_native_tls_key = TLS_OUT_OF_INDEXES;
+
+// g_last_used_tls_key is the high-water-mark of allocated thread local storage.
+// Each allocation is an index into our g_tls_destructors[].  Each such index is
+// assigned to the instance variable slot_ in a ThreadLocalStorage::Slot
+// instance.  We reserve the value slot_ == 0 to indicate that the corresponding
+// instance of ThreadLocalStorage::Slot has been freed (i.e., destructor called,
+// etc.).  This reserved use of 0 is then stated as the initial value of
+// g_last_used_tls_key, so that the first issued index will be 1.
+long g_last_used_tls_key = 0;
+
+// The maximum number of 'slots' in our thread local storage stack.
+const int kThreadLocalStorageSize = 64;
+
+// The maximum number of times to try to clear slots by calling destructors.
+// Use pthread naming convention for clarity.
+const int kMaxDestructorIterations = kThreadLocalStorageSize;
+
+// An array of destructor function pointers for the slots.  If a slot has a
+// destructor, it will be stored in its corresponding entry in this array.
+// The elements are volatile to ensure that when the compiler reads the value
+// to potentially call the destructor, it does so once, and that value is tested
+// for null-ness and then used. Yes, that would be a weird de-optimization,
+// but I can imagine some register machines where it was just as easy to
+// re-fetch an array element, and I want to be sure a call to free the key
+// (i.e., null out the destructor entry) that happens on a separate thread can't
+// hurt the racy calls to the destructors on another thread.
+volatile base::ThreadLocalStorage::TLSDestructorFunc
+    g_tls_destructors[kThreadLocalStorageSize];
+
+void** ConstructTlsVector() {
+  if (g_native_tls_key == TLS_OUT_OF_INDEXES) {
+    long value = TlsAlloc();
+    DCHECK(value != TLS_OUT_OF_INDEXES);
+
+    // Atomically test-and-set the tls_key.  If the key is TLS_OUT_OF_INDEXES,
+    // go ahead and set it.  Otherwise, do nothing, as another
+    // thread already did our dirty work.
+    if (TLS_OUT_OF_INDEXES != InterlockedCompareExchange(
+            &g_native_tls_key, value, TLS_OUT_OF_INDEXES)) {
+      // We've been shortcut. Another thread replaced g_native_tls_key first so
+      // we need to destroy our index and use the one the other thread got
+      // first.
+      TlsFree(value);
+    }
+  }
+  DCHECK(!TlsGetValue(g_native_tls_key));
+
+  // Some allocators, such as TCMalloc, make use of thread local storage.
+  // As a result, any attempt to call new (or malloc) will lazily cause such a
+  // system to initialize, which will include registering for a TLS key.  If we
+  // are not careful here, then that request to create a key will call new back,
+  // and we'll have an infinite loop.  We avoid that as follows:
+  // Use a stack allocated vector, so that we don't have dependence on our
+  // allocator until our service is in place.  (i.e., don't even call new until
+  // after we're setup)
+  void* stack_allocated_tls_data[kThreadLocalStorageSize];
+  memset(stack_allocated_tls_data, 0, sizeof(stack_allocated_tls_data));
+  // Ensure that any rentrant calls change the temp version.
+  TlsSetValue(g_native_tls_key, stack_allocated_tls_data);
+
+  // Allocate an array to store our data.
+  void** tls_data = new void*[kThreadLocalStorageSize];
+  memcpy(tls_data, stack_allocated_tls_data, sizeof(stack_allocated_tls_data));
+  TlsSetValue(g_native_tls_key, tls_data);
+  return tls_data;
+}
+
+// Called when we terminate a thread, this function calls any TLS destructors
+// that are pending for this thread.
+void WinThreadExit() {
+  if (g_native_tls_key == TLS_OUT_OF_INDEXES)
+    return;
+
+  void** tls_data = static_cast<void**>(TlsGetValue(g_native_tls_key));
+  // Maybe we have never initialized TLS for this thread.
+  if (!tls_data)
+    return;
+
+  // Some allocators, such as TCMalloc, use TLS.  As a result, when a thread
+  // terminates, one of the destructor calls we make may be to shut down an
+  // allocator.  We have to be careful that after we've shutdown all of the
+  // known destructors (perchance including an allocator), that we don't call
+  // the allocator and cause it to resurrect itself (with no possibly destructor
+  // call to follow).  We handle this problem as follows:
+  // Switch to using a stack allocated vector, so that we don't have dependence
+  // on our allocator after we have called all g_tls_destructors.  (i.e., don't
+  // even call delete[] after we're done with destructors.)
+  void* stack_allocated_tls_data[kThreadLocalStorageSize];
+  memcpy(stack_allocated_tls_data, tls_data, sizeof(stack_allocated_tls_data));
+  // Ensure that any re-entrant calls change the temp version.
+  TlsSetValue(g_native_tls_key, stack_allocated_tls_data);
+  delete[] tls_data;  // Our last dependence on an allocator.
+
+  int remaining_attempts = kMaxDestructorIterations;
+  bool need_to_scan_destructors = true;
+  while (need_to_scan_destructors) {
+    need_to_scan_destructors = false;
+    // Try to destroy the first-created-slot (which is slot 1) in our last
+    // destructor call.  That user was able to function, and define a slot with
+    // no other services running, so perhaps it is a basic service (like an
+    // allocator) and should also be destroyed last.  If we get the order wrong,
+    // then we'll itterate several more times, so it is really not that
+    // critical (but it might help).
+    for (int slot = g_last_used_tls_key; slot > 0; --slot) {
+      void* value = stack_allocated_tls_data[slot];
+      if (value == NULL)
+        continue;
+      base::ThreadLocalStorage::TLSDestructorFunc destructor =
+          g_tls_destructors[slot];
+      if (destructor == NULL)
+        continue;
+      stack_allocated_tls_data[slot] = NULL;  // pre-clear the slot.
+      destructor(value);
+      // Any destructor might have called a different service, which then set
+      // a different slot to a non-NULL value.  Hence we need to check
+      // the whole vector again.  This is a pthread standard.
+      need_to_scan_destructors = true;
+    }
+    if (--remaining_attempts <= 0) {
+      NOTREACHED();  // Destructors might not have been called.
+      break;
+    }
+  }
+
+  // Remove our stack allocated vector.
+  TlsSetValue(g_native_tls_key, NULL);
+}
+
+}  // namespace
+
+namespace base {
+
+ThreadLocalStorage::Slot::Slot(TLSDestructorFunc destructor) {
+  initialized_ = false;
+  slot_ = 0;
+  Initialize(destructor);
+}
+
+bool ThreadLocalStorage::StaticSlot::Initialize(TLSDestructorFunc destructor) {
+  if (g_native_tls_key == TLS_OUT_OF_INDEXES || !TlsGetValue(g_native_tls_key))
+    ConstructTlsVector();
+
+  // Grab a new slot.
+  slot_ = InterlockedIncrement(&g_last_used_tls_key);
+  DCHECK_GT(slot_, 0);
+  if (slot_ >= kThreadLocalStorageSize) {
+    NOTREACHED();
+    return false;
+  }
+
+  // Setup our destructor.
+  g_tls_destructors[slot_] = destructor;
+  initialized_ = true;
+  return true;
+}
+
+void ThreadLocalStorage::StaticSlot::Free() {
+  // At this time, we don't reclaim old indices for TLS slots.
+  // So all we need to do is wipe the destructor.
+  DCHECK_GT(slot_, 0);
+  DCHECK_LT(slot_, kThreadLocalStorageSize);
+  g_tls_destructors[slot_] = NULL;
+  slot_ = 0;
+  initialized_ = false;
+}
+
+void* ThreadLocalStorage::StaticSlot::Get() const {
+  void** tls_data = static_cast<void**>(TlsGetValue(g_native_tls_key));
+  if (!tls_data)
+    tls_data = ConstructTlsVector();
+  DCHECK_GT(slot_, 0);
+  DCHECK_LT(slot_, kThreadLocalStorageSize);
+  return tls_data[slot_];
+}
+
+void ThreadLocalStorage::StaticSlot::Set(void* value) {
+  void** tls_data = static_cast<void**>(TlsGetValue(g_native_tls_key));
+  if (!tls_data)
+    tls_data = ConstructTlsVector();
+  DCHECK_GT(slot_, 0);
+  DCHECK_LT(slot_, kThreadLocalStorageSize);
+  tls_data[slot_] = value;
+}
+
+}  // namespace base
+
+// Thread Termination Callbacks.
+// Windows doesn't support a per-thread destructor with its
+// TLS primitives.  So, we build it manually by inserting a
+// function to be called on each thread's exit.
+// This magic is from http://www.codeproject.com/threads/tls.asp
+// and it works for VC++ 7.0 and later.
+
+// Force a reference to _tls_used to make the linker create the TLS directory
+// if it's not already there.  (e.g. if __declspec(thread) is not used).
+// Force a reference to p_thread_callback_base to prevent whole program
+// optimization from discarding the variable.
+#ifdef _WIN64
+
+#pragma comment(linker, "/INCLUDE:_tls_used")
+#pragma comment(linker, "/INCLUDE:p_thread_callback_base")
+
+#else  // _WIN64
+
+#pragma comment(linker, "/INCLUDE:__tls_used")
+#pragma comment(linker, "/INCLUDE:_p_thread_callback_base")
+
+#endif  // _WIN64
+
+// Static callback function to call with each thread termination.
+void NTAPI OnThreadExit(PVOID module, DWORD reason, PVOID reserved) {
+  // On XP SP0 & SP1, the DLL_PROCESS_ATTACH is never seen. It is sent on SP2+
+  // and on W2K and W2K3. So don't assume it is sent.
+  if (DLL_THREAD_DETACH == reason || DLL_PROCESS_DETACH == reason)
+    WinThreadExit();
+}
+
+// .CRT$XLA to .CRT$XLZ is an array of PIMAGE_TLS_CALLBACK pointers that are
+// called automatically by the OS loader code (not the CRT) when the module is
+// loaded and on thread creation. They are NOT called if the module has been
+// loaded by a LoadLibrary() call. It must have implicitly been loaded at
+// process startup.
+// By implicitly loaded, I mean that it is directly referenced by the main EXE
+// or by one of its dependent DLLs. Delay-loaded DLL doesn't count as being
+// implicitly loaded.
+//
+// See VC\crt\src\tlssup.c for reference.
+
+// extern "C" suppresses C++ name mangling so we know the symbol name for the
+// linker /INCLUDE:symbol pragma above.
+extern "C" {
+// The linker must not discard p_thread_callback_base.  (We force a reference
+// to this variable with a linker /INCLUDE:symbol pragma to ensure that.) If
+// this variable is discarded, the OnThreadExit function will never be called.
+#ifdef _WIN64
+
+// .CRT section is merged with .rdata on x64 so it must be constant data.
+#pragma const_seg(".CRT$XLB")
+// When defining a const variable, it must have external linkage to be sure the
+// linker doesn't discard it.
+extern const PIMAGE_TLS_CALLBACK p_thread_callback_base;
+const PIMAGE_TLS_CALLBACK p_thread_callback_base = OnThreadExit;
+
+// Reset the default section.
+#pragma const_seg()
+
+#else  // _WIN64
+
+#pragma data_seg(".CRT$XLB")
+PIMAGE_TLS_CALLBACK p_thread_callback_base = OnThreadExit;
+
+// Reset the default section.
+#pragma data_seg()
+
+#endif  // _WIN64
+}  // extern "C"
diff --git a/chromium/base/threading/thread_local_unittest.cc b/chromium/base/threading/thread_local_unittest.cc
new file mode 100644
index 00000000000..b125a484063
--- /dev/null
+++ b/chromium/base/threading/thread_local_unittest.cc
@@ -0,0 +1,169 @@
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "base/logging.h"
+#include "base/threading/simple_thread.h"
+#include "base/threading/thread_local.h"
+#include "base/synchronization/waitable_event.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace base {
+
+namespace {
+
+class ThreadLocalTesterBase : public base::DelegateSimpleThreadPool::Delegate {
+ public:
+  typedef base::ThreadLocalPointer<ThreadLocalTesterBase> TLPType;
+
+  ThreadLocalTesterBase(TLPType* tlp, base::WaitableEvent* done)
+      : tlp_(tlp),
+        done_(done) {
+  }
+  virtual ~ThreadLocalTesterBase() {}
+
+ protected:
+  TLPType* tlp_;
+  base::WaitableEvent* done_;
+};
+
+class SetThreadLocal : public ThreadLocalTesterBase {
+ public:
+  SetThreadLocal(TLPType* tlp, base::WaitableEvent* done)
+      : ThreadLocalTesterBase(tlp, done),
+        val_(NULL) {
+  }
+  virtual ~SetThreadLocal() {}
+
+  void set_value(ThreadLocalTesterBase* val) { val_ = val; }
+
+  virtual void Run() OVERRIDE {
+    DCHECK(!done_->IsSignaled());
+    tlp_->Set(val_);
+    done_->Signal();
+  }
+
+ private:
+  ThreadLocalTesterBase* val_;
+};
+
+class GetThreadLocal : public ThreadLocalTesterBase {
+ public:
+  GetThreadLocal(TLPType* tlp, base::WaitableEvent* done)
+      : ThreadLocalTesterBase(tlp, done),
+        ptr_(NULL) {
+  }
+  virtual ~GetThreadLocal() {}
+
+  void set_ptr(ThreadLocalTesterBase** ptr) { ptr_ = ptr; }
+
+  virtual void Run() OVERRIDE {
+    DCHECK(!done_->IsSignaled());
+    *ptr_ = tlp_->Get();
+    done_->Signal();
+  }
+
+ private:
+  ThreadLocalTesterBase** ptr_;
+};
+
+}  // namespace
+
+// In this test, we start 2 threads which will access a ThreadLocalPointer.  We
+// make sure the default is NULL, and the pointers are unique to the threads.
+TEST(ThreadLocalTest, Pointer) {
+  base::DelegateSimpleThreadPool tp1("ThreadLocalTest tp1", 1);
+  base::DelegateSimpleThreadPool tp2("ThreadLocalTest tp1", 1);
+  tp1.Start();
+  tp2.Start();
+
+  base::ThreadLocalPointer<ThreadLocalTesterBase> tlp;
+
+  static ThreadLocalTesterBase* const kBogusPointer =
+      reinterpret_cast<ThreadLocalTesterBase*>(0x1234);
+
+  ThreadLocalTesterBase* tls_val;
+  base::WaitableEvent done(true, false);
+
+  GetThreadLocal getter(&tlp, &done);
+  getter.set_ptr(&tls_val);
+
+  // Check that both threads defaulted to NULL.
+  tls_val = kBogusPointer;
+  done.Reset();
+  tp1.AddWork(&getter);
+  done.Wait();
+  EXPECT_EQ(static_cast<ThreadLocalTesterBase*>(NULL), tls_val);
+
+  tls_val = kBogusPointer;
+  done.Reset();
+  tp2.AddWork(&getter);
+  done.Wait();
+  EXPECT_EQ(static_cast<ThreadLocalTesterBase*>(NULL), tls_val);
+
+
+  SetThreadLocal setter(&tlp, &done);
+  setter.set_value(kBogusPointer);
+
+  // Have thread 1 set their pointer value to kBogusPointer.
+  done.Reset();
+  tp1.AddWork(&setter);
+  done.Wait();
+
+  tls_val = NULL;
+  done.Reset();
+  tp1.AddWork(&getter);
+  done.Wait();
+  EXPECT_EQ(kBogusPointer, tls_val);
+
+  // Make sure thread 2 is still NULL
+  tls_val = kBogusPointer;
+  done.Reset();
+  tp2.AddWork(&getter);
+  done.Wait();
+  EXPECT_EQ(static_cast<ThreadLocalTesterBase*>(NULL), tls_val);
+
+  // Set thread 2 to kBogusPointer + 1.
+  setter.set_value(kBogusPointer + 1);
+
+  done.Reset();
+  tp2.AddWork(&setter);
+  done.Wait();
+
+  tls_val = NULL;
+  done.Reset();
+  tp2.AddWork(&getter);
+  done.Wait();
+  EXPECT_EQ(kBogusPointer + 1, tls_val);
+
+  // Make sure thread 1 is still kBogusPointer.
+  tls_val = NULL;
+  done.Reset();
+  tp1.AddWork(&getter);
+  done.Wait();
+  EXPECT_EQ(kBogusPointer, tls_val);
+
+  tp1.JoinAll();
+  tp2.JoinAll();
+}
+
+TEST(ThreadLocalTest, Boolean) {
+  {
+    base::ThreadLocalBoolean tlb;
+    EXPECT_FALSE(tlb.Get());
+
+    tlb.Set(false);
+    EXPECT_FALSE(tlb.Get());
+
+    tlb.Set(true);
+    EXPECT_TRUE(tlb.Get());
+  }
+
+  // Our slot should have been freed, we're all reset.
+  {
+    base::ThreadLocalBoolean tlb;
+    EXPECT_FALSE(tlb.Get());
+  }
+}
+
+}  // namespace base
diff --git a/chromium/base/threading/thread_local_win.cc b/chromium/base/threading/thread_local_win.cc
new file mode 100644
index 00000000000..56d3a3ac7f2
--- /dev/null
+++ b/chromium/base/threading/thread_local_win.cc
@@ -0,0 +1,42 @@
+// Copyright (c) 2010 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "base/threading/thread_local.h"
+
+#include <windows.h>
+
+#include "base/logging.h"
+
+namespace base {
+
+namespace internal {
+
+// static
+void ThreadLocalPlatform::AllocateSlot(SlotType& slot) {
+  slot = TlsAlloc();
+  CHECK_NE(slot, TLS_OUT_OF_INDEXES);
+}
+
+// static
+void ThreadLocalPlatform::FreeSlot(SlotType& slot) {
+  if (!TlsFree(slot)) {
+    NOTREACHED() << "Failed to deallocate tls slot with TlsFree().";
+  }
+}
+
+// static
+void* ThreadLocalPlatform::GetValueFromSlot(SlotType& slot) {
+  return TlsGetValue(slot);
+}
+
+// static
+void ThreadLocalPlatform::SetValueInSlot(SlotType& slot, void* value) {
+  if (!TlsSetValue(slot, value)) {
+    LOG(FATAL) << "Failed to TlsSetValue().";
+  }
+}
+
+}  // namespace internal
+
+}  // namespace base
diff --git a/chromium/base/threading/thread_restrictions.cc b/chromium/base/threading/thread_restrictions.cc
new file mode 100644
index 00000000000..871f2dc874c
--- /dev/null
+++ b/chromium/base/threading/thread_restrictions.cc
@@ -0,0 +1,85 @@
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "base/threading/thread_restrictions.h"
+
+#if ENABLE_THREAD_RESTRICTIONS
+
+#include "base/lazy_instance.h"
+#include "base/logging.h"
+#include "base/threading/thread_local.h"
+
+namespace base {
+
+namespace {
+
+LazyInstance<ThreadLocalBoolean>::Leaky
+    g_io_disallowed = LAZY_INSTANCE_INITIALIZER;
+
+LazyInstance<ThreadLocalBoolean>::Leaky
+    g_singleton_disallowed = LAZY_INSTANCE_INITIALIZER;
+
+LazyInstance<ThreadLocalBoolean>::Leaky
+    g_wait_disallowed = LAZY_INSTANCE_INITIALIZER;
+
+}  // anonymous namespace
+
+// static
+bool ThreadRestrictions::SetIOAllowed(bool allowed) {
+  bool previous_disallowed = g_io_disallowed.Get().Get();
+  g_io_disallowed.Get().Set(!allowed);
+  return !previous_disallowed;
+}
+
+// static
+void ThreadRestrictions::AssertIOAllowed() {
+  if (g_io_disallowed.Get().Get()) {
+    LOG(FATAL) <<
+        "Function marked as IO-only was called from a thread that "
+        "disallows IO!  If this thread really should be allowed to "
+        "make IO calls, adjust the call to "
+        "base::ThreadRestrictions::SetIOAllowed() in this thread's "
+        "startup.";
+  }
+}
+
+// static
+bool ThreadRestrictions::SetSingletonAllowed(bool allowed) {
+  bool previous_disallowed = g_singleton_disallowed.Get().Get();
+  g_singleton_disallowed.Get().Set(!allowed);
+  return !previous_disallowed;
+}
+
+// static
+void ThreadRestrictions::AssertSingletonAllowed() {
+  if (g_singleton_disallowed.Get().Get()) {
+    LOG(FATAL) << "LazyInstance/Singleton is not allowed to be used on this "
+               << "thread.  Most likely it's because this thread is not "
+               << "joinable, so AtExitManager may have deleted the object "
+               << "on shutdown, leading to a potential shutdown crash.";
+  }
+}
+
+// static
+void ThreadRestrictions::DisallowWaiting() {
+  g_wait_disallowed.Get().Set(true);
+}
+
+// static
+void ThreadRestrictions::AssertWaitAllowed() {
+  if (g_wait_disallowed.Get().Get()) {
+    LOG(FATAL) << "Waiting is not allowed to be used on this thread to prevent"
+               << "jank and deadlock.";
+  }
+}
+
+bool ThreadRestrictions::SetWaitAllowed(bool allowed) {
+  bool previous_disallowed = g_wait_disallowed.Get().Get();
+  g_wait_disallowed.Get().Set(!allowed);
+  return !previous_disallowed;
+}
+
+}  // namespace base
+
+#endif  // ENABLE_THREAD_RESTRICTIONS
diff --git a/chromium/base/threading/thread_restrictions.h b/chromium/base/threading/thread_restrictions.h
new file mode 100644
index 00000000000..595b97060e0
--- /dev/null
+++ b/chromium/base/threading/thread_restrictions.h
@@ -0,0 +1,247 @@
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef BASE_THREADING_THREAD_RESTRICTIONS_H_
+#define BASE_THREADING_THREAD_RESTRICTIONS_H_
+
+#include "base/base_export.h"
+#include "base/basictypes.h"
+
+// See comment at top of thread_checker.h
+#if (!defined(NDEBUG) || defined(DCHECK_ALWAYS_ON))
+#define ENABLE_THREAD_RESTRICTIONS 1
+#else
+#define ENABLE_THREAD_RESTRICTIONS 0
+#endif
+
+class AcceleratedPresenter;
+class BrowserProcessImpl;
+class HistogramSynchronizer;
+class MetricsService;
+class NativeBackendKWallet;
+class ScopedAllowWaitForLegacyWebViewApi;
+class TestingAutomationProvider;
+
+namespace browser_sync {
+class NonFrontendDataTypeController;
+class UIModelWorker;
+}
+namespace cc {
+class CompletionEvent;
+}
+namespace chromeos {
+class AudioMixerAlsa;
+class BlockingMethodCaller;
+namespace system {
+class StatisticsProviderImpl;
+}
+}
+namespace chrome_browser_net {
+class Predictor;
+}
+namespace content {
+class BrowserGpuChannelHostFactory;
+class BrowserTestBase;
+class GLHelper;
+class GpuChannelHost;
+class RenderWidgetHelper;
+class ScopedAllowWaitForAndroidLayoutTests;
+class TextInputClientMac;
+}
+namespace dbus {
+class Bus;
+}
+namespace disk_cache {
+class BackendImpl;
+class InFlightIO;
+}
+namespace media {
+class AudioOutputController;
+}
+namespace net {
+class FileStreamPosix;
+class FileStreamWin;
+namespace internal {
+class AddressTrackerLinux;
+}
+}
+
+namespace remoting {
+class AutoThread;
+}
+
+namespace base {
+
+namespace android {
+class JavaHandlerThread;
+}
+
+class SequencedWorkerPool;
+class SimpleThread;
+class Thread;
+class ThreadTestHelper;
+
+// Certain behavior is disallowed on certain threads.  ThreadRestrictions helps
+// enforce these rules.  Examples of such rules:
+//
+// * Do not do blocking IO (makes the thread janky)
+// * Do not access Singleton/LazyInstance (may lead to shutdown crashes)
+//
+// Here's more about how the protection works:
+//
+// 1) If a thread should not be allowed to make IO calls, mark it:
+//      base::ThreadRestrictions::SetIOAllowed(false);
+//    By default, threads *are* allowed to make IO calls.
+//    In Chrome browser code, IO calls should be proxied to the File thread.
+//
+// 2) If a function makes a call that will go out to disk, check whether the
+//    current thread is allowed:
+//      base::ThreadRestrictions::AssertIOAllowed();
+//
+//
+// Style tip: where should you put AssertIOAllowed checks?  It's best
+// if you put them as close to the disk access as possible, at the
+// lowest level.  This rule is simple to follow and helps catch all
+// callers.  For example, if your function GoDoSomeBlockingDiskCall()
+// only calls other functions in Chrome and not fopen(), you should go
+// add the AssertIOAllowed checks in the helper functions.
+
+class BASE_EXPORT ThreadRestrictions {
+ public:
+  // Constructing a ScopedAllowIO temporarily allows IO for the current
+  // thread.  Doing this is almost certainly always incorrect.
+  class BASE_EXPORT ScopedAllowIO {
+   public:
+    ScopedAllowIO() { previous_value_ = SetIOAllowed(true); }
+    ~ScopedAllowIO() { SetIOAllowed(previous_value_); }
+   private:
+    // Whether IO is allowed when the ScopedAllowIO was constructed.
+    bool previous_value_;
+
+    DISALLOW_COPY_AND_ASSIGN(ScopedAllowIO);
+  };
+
+  // Constructing a ScopedAllowSingleton temporarily allows accessing for the
+  // current thread.  Doing this is almost always incorrect.
+  class BASE_EXPORT ScopedAllowSingleton {
+   public:
+    ScopedAllowSingleton() { previous_value_ = SetSingletonAllowed(true); }
+    ~ScopedAllowSingleton() { SetSingletonAllowed(previous_value_); }
+   private:
+    // Whether singleton use is allowed when the ScopedAllowSingleton was
+    // constructed.
+    bool previous_value_;
+
+    DISALLOW_COPY_AND_ASSIGN(ScopedAllowSingleton);
+  };
+
+#if ENABLE_THREAD_RESTRICTIONS
+  // Set whether the current thread to make IO calls.
+  // Threads start out in the *allowed* state.
+  // Returns the previous value.
+  static bool SetIOAllowed(bool allowed);
+
+  // Check whether the current thread is allowed to make IO calls,
+  // and DCHECK if not.  See the block comment above the class for
+  // a discussion of where to add these checks.
+  static void AssertIOAllowed();
+
+  // Set whether the current thread can use singletons.  Returns the previous
+  // value.
+  static bool SetSingletonAllowed(bool allowed);
+
+  // Check whether the current thread is allowed to use singletons (Singleton /
+  // LazyInstance).  DCHECKs if not.
+  static void AssertSingletonAllowed();
+
+  // Disable waiting on the current thread. Threads start out in the *allowed*
+  // state. Returns the previous value.
+  static void DisallowWaiting();
+
+  // Check whether the current thread is allowed to wait, and DCHECK if not.
+  static void AssertWaitAllowed();
+#else
+  // Inline the empty definitions of these functions so that they can be
+  // compiled out.
+  static bool SetIOAllowed(bool allowed) { return true; }
+  static void AssertIOAllowed() {}
+  static bool SetSingletonAllowed(bool allowed) { return true; }
+  static void AssertSingletonAllowed() {}
+  static void DisallowWaiting() {}
+  static void AssertWaitAllowed() {}
+#endif
+
+ private:
+  // DO NOT ADD ANY OTHER FRIEND STATEMENTS, talk to jam or brettw first.
+  // BEGIN ALLOWED USAGE.
+  friend class content::BrowserTestBase;
+  friend class content::RenderWidgetHelper;
+  friend class content::ScopedAllowWaitForAndroidLayoutTests;
+  friend class ::HistogramSynchronizer;
+  friend class ::ScopedAllowWaitForLegacyWebViewApi;
+  friend class ::TestingAutomationProvider;
+  friend class cc::CompletionEvent;
+  friend class remoting::AutoThread;
+  friend class MessagePumpDefault;
+  friend class SequencedWorkerPool;
+  friend class SimpleThread;
+  friend class Thread;
+  friend class ThreadTestHelper;
+  friend class PlatformThread;
+  friend class android::JavaHandlerThread;
+
+  // END ALLOWED USAGE.
+  // BEGIN USAGE THAT NEEDS TO BE FIXED.
+  friend class ::chromeos::AudioMixerAlsa;        // http://crbug.com/125206
+  friend class ::chromeos::BlockingMethodCaller;  // http://crbug.com/125360
+  friend class ::chromeos::system::StatisticsProviderImpl;  // http://crbug.com/125385
+  friend class browser_sync::NonFrontendDataTypeController;  // http://crbug.com/19757
+  friend class browser_sync::UIModelWorker;       // http://crbug.com/19757
+  friend class chrome_browser_net::Predictor;     // http://crbug.com/78451
+  friend class
+      content::BrowserGpuChannelHostFactory;      // http://crbug.com/125248
+  friend class content::GLHelper;                 // http://crbug.com/125415
+  friend class content::GpuChannelHost;           // http://crbug.com/125264
+  friend class content::TextInputClientMac;       // http://crbug.com/121917
+  friend class dbus::Bus;                         // http://crbug.com/125222
+  friend class disk_cache::BackendImpl;           // http://crbug.com/74623
+  friend class disk_cache::InFlightIO;            // http://crbug.com/74623
+  friend class media::AudioOutputController;      // http://crbug.com/120973
+  friend class net::FileStreamPosix;              // http://crbug.com/115067
+  friend class net::FileStreamWin;                // http://crbug.com/115067
+  friend class net::internal::AddressTrackerLinux;  // http://crbug.com/125097
+  friend class ::AcceleratedPresenter;            // http://crbug.com/125391
+  friend class ::BrowserProcessImpl;              // http://crbug.com/125207
+  friend class ::MetricsService;                  // http://crbug.com/124954
+  friend class ::NativeBackendKWallet;            // http://crbug.com/125331
+  // END USAGE THAT NEEDS TO BE FIXED.
+
+#if ENABLE_THREAD_RESTRICTIONS
+  static bool SetWaitAllowed(bool allowed);
+#else
+  static bool SetWaitAllowed(bool allowed) { return true; }
+#endif
+
+  // Constructing a ScopedAllowWait temporarily allows waiting on the current
+  // thread.  Doing this is almost always incorrect, which is why we limit who
+  // can use this through friend. If you find yourself needing to use this, find
+  // another way. Talk to jam or brettw.
+  class BASE_EXPORT ScopedAllowWait {
+   public:
+    ScopedAllowWait() { previous_value_ = SetWaitAllowed(true); }
+    ~ScopedAllowWait() { SetWaitAllowed(previous_value_); }
+   private:
+    // Whether singleton use is allowed when the ScopedAllowWait was
+    // constructed.
+    bool previous_value_;
+
+    DISALLOW_COPY_AND_ASSIGN(ScopedAllowWait);
+  };
+
+  DISALLOW_IMPLICIT_CONSTRUCTORS(ThreadRestrictions);
+};
+
+}  // namespace base
+
+#endif  // BASE_THREADING_THREAD_RESTRICTIONS_H_
diff --git a/chromium/base/threading/thread_unittest.cc b/chromium/base/threading/thread_unittest.cc
new file mode 100644
index 00000000000..8bd817c75bc
--- /dev/null
+++ b/chromium/base/threading/thread_unittest.cc
@@ -0,0 +1,239 @@
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "base/threading/thread.h"
+
+#include <vector>
+
+#include "base/bind.h"
+#include "base/message_loop/message_loop.h"
+#include "base/third_party/dynamic_annotations/dynamic_annotations.h"
+#include "testing/gtest/include/gtest/gtest.h"
+#include "testing/platform_test.h"
+
+using base::Thread;
+
+typedef PlatformTest ThreadTest;
+
+namespace {
+
+void ToggleValue(bool* value) {
+  ANNOTATE_BENIGN_RACE(value, "Test-only data race on boolean "
+                       "in base/thread_unittest");
+  *value = !*value;
+}
+
+class SleepInsideInitThread : public Thread {
+ public:
+  SleepInsideInitThread() : Thread("none") {
+    init_called_ = false;
+    ANNOTATE_BENIGN_RACE(
+        this, "Benign test-only data race on vptr - http://crbug.com/98219");
+  }
+  virtual ~SleepInsideInitThread() {
+    Stop();
+  }
+
+  virtual void Init() OVERRIDE {
+    base::PlatformThread::Sleep(base::TimeDelta::FromMilliseconds(500));
+    init_called_ = true;
+  }
+  bool InitCalled() { return init_called_; }
+ private:
+  bool init_called_;
+};
+
+enum ThreadEvent {
+  // Thread::Init() was called.
+  THREAD_EVENT_INIT = 0,
+
+  // The MessageLoop for the thread was deleted.
+  THREAD_EVENT_MESSAGE_LOOP_DESTROYED,
+
+  // Thread::CleanUp() was called.
+  THREAD_EVENT_CLEANUP,
+
+  // Keep at end of list.
+  THREAD_NUM_EVENTS
+};
+
+typedef std::vector<ThreadEvent> EventList;
+
+class CaptureToEventList : public Thread {
+ public:
+  // This Thread pushes events into the vector |event_list| to show
+  // the order they occured in. |event_list| must remain valid for the
+  // lifetime of this thread.
+  explicit CaptureToEventList(EventList* event_list)
+      : Thread("none"),
+        event_list_(event_list) {
+  }
+
+  virtual ~CaptureToEventList() {
+    Stop();
+  }
+
+  virtual void Init() OVERRIDE {
+    event_list_->push_back(THREAD_EVENT_INIT);
+  }
+
+  virtual void CleanUp() OVERRIDE {
+    event_list_->push_back(THREAD_EVENT_CLEANUP);
+  }
+
+ private:
+  EventList* event_list_;
+};
+
+// Observer that writes a value into |event_list| when a message loop has been
+// destroyed.
+class CapturingDestructionObserver
+    : public base::MessageLoop::DestructionObserver {
+ public:
+  // |event_list| must remain valid throughout the observer's lifetime.
+  explicit CapturingDestructionObserver(EventList* event_list)
+      : event_list_(event_list) {
+  }
+
+  // DestructionObserver implementation:
+  virtual void WillDestroyCurrentMessageLoop() OVERRIDE {
+    event_list_->push_back(THREAD_EVENT_MESSAGE_LOOP_DESTROYED);
+    event_list_ = NULL;
+  }
+
+ private:
+  EventList* event_list_;
+};
+
+// Task that adds a destruction observer to the current message loop.
+void RegisterDestructionObserver(
+    base::MessageLoop::DestructionObserver* observer) {
+  base::MessageLoop::current()->AddDestructionObserver(observer);
+}
+
+}  // namespace
+
+TEST_F(ThreadTest, Restart) {
+  Thread a("Restart");
+  a.Stop();
+  EXPECT_FALSE(a.message_loop());
+  EXPECT_FALSE(a.IsRunning());
+  EXPECT_TRUE(a.Start());
+  EXPECT_TRUE(a.message_loop());
+  EXPECT_TRUE(a.IsRunning());
+  a.Stop();
+  EXPECT_FALSE(a.message_loop());
+  EXPECT_FALSE(a.IsRunning());
+  EXPECT_TRUE(a.Start());
+  EXPECT_TRUE(a.message_loop());
+  EXPECT_TRUE(a.IsRunning());
+  a.Stop();
+  EXPECT_FALSE(a.message_loop());
+  EXPECT_FALSE(a.IsRunning());
+  a.Stop();
+  EXPECT_FALSE(a.message_loop());
+  EXPECT_FALSE(a.IsRunning());
+}
+
+TEST_F(ThreadTest, StartWithOptions_StackSize) {
+  Thread a("StartWithStackSize");
+  // Ensure that the thread can work with only 12 kb and still process a
+  // message.
+  Thread::Options options;
+  options.stack_size = 12*1024;
+  EXPECT_TRUE(a.StartWithOptions(options));
+  EXPECT_TRUE(a.message_loop());
+  EXPECT_TRUE(a.IsRunning());
+
+  bool was_invoked = false;
+  a.message_loop()->PostTask(FROM_HERE, base::Bind(&ToggleValue, &was_invoked));
+
+  // wait for the task to run (we could use a kernel event here
+  // instead to avoid busy waiting, but this is sufficient for
+  // testing purposes).
+  for (int i = 100; i >= 0 && !was_invoked; --i) {
+    base::PlatformThread::Sleep(base::TimeDelta::FromMilliseconds(10));
+  }
+  EXPECT_TRUE(was_invoked);
+}
+
+TEST_F(ThreadTest, TwoTasks) {
+  bool was_invoked = false;
+  {
+    Thread a("TwoTasks");
+    EXPECT_TRUE(a.Start());
+    EXPECT_TRUE(a.message_loop());
+
+    // Test that all events are dispatched before the Thread object is
+    // destroyed.  We do this by dispatching a sleep event before the
+    // event that will toggle our sentinel value.
+    a.message_loop()->PostTask(
+        FROM_HERE,
+        base::Bind(
+            static_cast<void (*)(base::TimeDelta)>(
+                &base::PlatformThread::Sleep),
+            base::TimeDelta::FromMilliseconds(20)));
+    a.message_loop()->PostTask(FROM_HERE, base::Bind(&ToggleValue,
+                                                     &was_invoked));
+  }
+  EXPECT_TRUE(was_invoked);
+}
+
+TEST_F(ThreadTest, StopSoon) {
+  Thread a("StopSoon");
+  EXPECT_TRUE(a.Start());
+  EXPECT_TRUE(a.message_loop());
+  EXPECT_TRUE(a.IsRunning());
+  a.StopSoon();
+  a.StopSoon();
+  a.Stop();
+  EXPECT_FALSE(a.message_loop());
+  EXPECT_FALSE(a.IsRunning());
+}
+
+TEST_F(ThreadTest, ThreadName) {
+  Thread a("ThreadName");
+  EXPECT_TRUE(a.Start());
+  EXPECT_EQ("ThreadName", a.thread_name());
+}
+
+// Make sure we can't use a thread between Start() and Init().
+TEST_F(ThreadTest, SleepInsideInit) {
+  SleepInsideInitThread t;
+  EXPECT_FALSE(t.InitCalled());
+  t.Start();
+  EXPECT_TRUE(t.InitCalled());
+}
+
+// Make sure that the destruction sequence is:
+//
+//  (1) Thread::CleanUp()
+//  (2) MessageLoop::~MessageLoop()
+//      MessageLoop::DestructionObservers called.
+TEST_F(ThreadTest, CleanUp) {
+  EventList captured_events;
+  CapturingDestructionObserver loop_destruction_observer(&captured_events);
+
+  {
+    // Start a thread which writes its event into |captured_events|.
+    CaptureToEventList t(&captured_events);
+    EXPECT_TRUE(t.Start());
+    EXPECT_TRUE(t.message_loop());
+    EXPECT_TRUE(t.IsRunning());
+
+    // Register an observer that writes into |captured_events| once the
+    // thread's message loop is destroyed.
+    t.message_loop()->PostTask(
+        FROM_HERE, base::Bind(&RegisterDestructionObserver,
+                              base::Unretained(&loop_destruction_observer)));
+
+    // Upon leaving this scope, the thread is deleted.
+  }
+
+  // Check the order of events during shutdown.
+  ASSERT_EQ(static_cast<size_t>(THREAD_NUM_EVENTS), captured_events.size());
+  EXPECT_EQ(THREAD_EVENT_INIT, captured_events[0]);
+  EXPECT_EQ(THREAD_EVENT_CLEANUP, captured_events[1]);
+  EXPECT_EQ(THREAD_EVENT_MESSAGE_LOOP_DESTROYED, captured_events[2]);
+}
diff --git a/chromium/base/threading/watchdog.cc b/chromium/base/threading/watchdog.cc
new file mode 100644
index 00000000000..a18efecc5f6
--- /dev/null
+++ b/chromium/base/threading/watchdog.cc
@@ -0,0 +1,178 @@
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "base/threading/watchdog.h"
+
+#include "base/compiler_specific.h"
+#include "base/lazy_instance.h"
+#include "base/logging.h"
+#include "base/threading/platform_thread.h"
+
+namespace base {
+
+namespace {
+
+// When the debugger breaks (when we alarm), all the other alarms that are
+// armed will expire (also alarm).  To diminish this effect, we track any
+// delay due to debugger breaks, and we *try* to adjust the effective start
+// time of other alarms to step past the debugging break.
+// Without this safety net, any alarm will typically trigger a host of follow
+// on alarms from callers that specify old times.
+
+// Lock for access of static data...
+LazyInstance<Lock>::Leaky g_static_lock = LAZY_INSTANCE_INITIALIZER;
+
+// When did we last alarm and get stuck (for a while) in a debugger?
+TimeTicks g_last_debugged_alarm_time;
+
+// How long did we sit on a break in the debugger?
+TimeDelta g_last_debugged_alarm_delay;
+
+}  // namespace
+
+// Start thread running in a Disarmed state.
+Watchdog::Watchdog(const TimeDelta& duration,
+                   const std::string& thread_watched_name,
+                   bool enabled)
+  : enabled_(enabled),
+    lock_(),
+    condition_variable_(&lock_),
+    state_(DISARMED),
+    duration_(duration),
+    thread_watched_name_(thread_watched_name),
+    delegate_(this) {
+  if (!enabled_)
+    return;  // Don't start thread, or doing anything really.
+  enabled_ = PlatformThread::Create(0,  // Default stack size.
+                                    &delegate_,
+                                    &handle_);
+  DCHECK(enabled_);
+}
+
+// Notify watchdog thread, and wait for it to finish up.
+Watchdog::~Watchdog() {
+  if (!enabled_)
+    return;
+  if (!IsJoinable())
+    Cleanup();
+  condition_variable_.Signal();
+  PlatformThread::Join(handle_);
+}
+
+void Watchdog::Cleanup() {
+  if (!enabled_)
+    return;
+  {
+    AutoLock lock(lock_);
+    state_ = SHUTDOWN;
+  }
+  condition_variable_.Signal();
+}
+
+bool Watchdog::IsJoinable() {
+  if (!enabled_)
+    return true;
+  AutoLock lock(lock_);
+  return (state_ == JOINABLE);
+}
+
+void Watchdog::Arm() {
+  ArmAtStartTime(TimeTicks::Now());
+}
+
+void Watchdog::ArmSomeTimeDeltaAgo(const TimeDelta& time_delta) {
+  ArmAtStartTime(TimeTicks::Now() - time_delta);
+}
+
+// Start clock for watchdog.
+void Watchdog::ArmAtStartTime(const TimeTicks start_time) {
+  {
+    AutoLock lock(lock_);
+    start_time_ = start_time;
+    state_ = ARMED;
+  }
+  // Force watchdog to wake up, and go to sleep with the timer ticking with the
+  // proper duration.
+  condition_variable_.Signal();
+}
+
+// Disable watchdog so that it won't do anything when time expires.
+void Watchdog::Disarm() {
+  AutoLock lock(lock_);
+  state_ = DISARMED;
+  // We don't need to signal, as the watchdog will eventually wake up, and it
+  // will check its state and time, and act accordingly.
+}
+
+void Watchdog::Alarm() {
+  DVLOG(1) << "Watchdog alarmed for " << thread_watched_name_;
+}
+
+//------------------------------------------------------------------------------
+// Internal private methods that the watchdog thread uses.
+
+void Watchdog::ThreadDelegate::ThreadMain() {
+  SetThreadName();
+  TimeDelta remaining_duration;
+  while (1) {
+    AutoLock lock(watchdog_->lock_);
+    while (DISARMED == watchdog_->state_)
+      watchdog_->condition_variable_.Wait();
+    if (SHUTDOWN == watchdog_->state_) {
+      watchdog_->state_ = JOINABLE;
+      return;
+    }
+    DCHECK(ARMED == watchdog_->state_);
+    remaining_duration = watchdog_->duration_ -
+        (TimeTicks::Now() - watchdog_->start_time_);
+    if (remaining_duration.InMilliseconds() > 0) {
+      // Spurios wake?  Timer drifts?  Go back to sleep for remaining time.
+      watchdog_->condition_variable_.TimedWait(remaining_duration);
+      continue;
+    }
+    // We overslept, so this seems like a real alarm.
+    // Watch out for a user that stopped the debugger on a different alarm!
+    {
+      AutoLock static_lock(*g_static_lock.Pointer());
+      if (g_last_debugged_alarm_time > watchdog_->start_time_) {
+        // False alarm: we started our clock before the debugger break (last
+        // alarm time).
+        watchdog_->start_time_ += g_last_debugged_alarm_delay;
+        if (g_last_debugged_alarm_time > watchdog_->start_time_)
+          // Too many alarms must have taken place.
+          watchdog_->state_ = DISARMED;
+        continue;
+      }
+    }
+    watchdog_->state_ = DISARMED;  // Only alarm at most once.
+    TimeTicks last_alarm_time = TimeTicks::Now();
+    {
+      AutoUnlock lock(watchdog_->lock_);
+      watchdog_->Alarm();  // Set a break point here to debug on alarms.
+    }
+    TimeDelta last_alarm_delay = TimeTicks::Now() - last_alarm_time;
+    if (last_alarm_delay <= TimeDelta::FromMilliseconds(2))
+      continue;
+    // Ignore race of two alarms/breaks going off at roughly the same time.
+    AutoLock static_lock(*g_static_lock.Pointer());
+    // This was a real debugger break.
+    g_last_debugged_alarm_time = last_alarm_time;
+    g_last_debugged_alarm_delay = last_alarm_delay;
+  }
+}
+
+void Watchdog::ThreadDelegate::SetThreadName() const {
+  std::string name = watchdog_->thread_watched_name_ + " Watchdog";
+  PlatformThread::SetName(name.c_str());
+  DVLOG(1) << "Watchdog active: " << name;
+}
+
+// static
+void Watchdog::ResetStaticData() {
+  AutoLock lock(*g_static_lock.Pointer());
+  g_last_debugged_alarm_time = TimeTicks();
+  g_last_debugged_alarm_delay = TimeDelta();
+}
+
+}  // namespace base
diff --git a/chromium/base/threading/watchdog.h b/chromium/base/threading/watchdog.h
new file mode 100644
index 00000000000..abcb4f12809
--- /dev/null
+++ b/chromium/base/threading/watchdog.h
@@ -0,0 +1,94 @@
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// The Watchdog class creates a second thread that can Alarm if a specific
+// duration of time passes without proper attention.  The duration of time is
+// specified at construction time.  The Watchdog may be used many times by
+// simply calling Arm() (to start timing) and Disarm() (to reset the timer).
+// The Watchdog is typically used under a debugger, where the stack traces on
+// other threads can be examined if/when the Watchdog alarms.
+
+// Some watchdogs will be enabled or disabled via command line switches. To
+// facilitate such code, an "enabled" argument for the constuctor can be used
+// to permanently disable the watchdog.  Disabled watchdogs don't even spawn
+// a second thread, and their methods call (Arm() and Disarm()) return very
+// quickly.
+
+#ifndef BASE_THREADING_WATCHDOG_H_
+#define BASE_THREADING_WATCHDOG_H_
+
+#include <string>
+
+#include "base/base_export.h"
+#include "base/compiler_specific.h"
+#include "base/synchronization/condition_variable.h"
+#include "base/synchronization/lock.h"
+#include "base/threading/platform_thread.h"
+#include "base/time/time.h"
+
+namespace base {
+
+class BASE_EXPORT Watchdog {
+ public:
+  // Constructor specifies how long the Watchdog will wait before alarming.
+  Watchdog(const TimeDelta& duration,
+           const std::string& thread_watched_name,
+           bool enabled);
+  virtual ~Watchdog();
+
+  // Notify watchdog thread to finish up. Sets the state_ to SHUTDOWN.
+  void Cleanup();
+
+  // Returns true if we state_ is JOINABLE (which indicates that Watchdog has
+  // exited).
+  bool IsJoinable();
+
+  // Start timing, and alarm when time expires (unless we're disarm()ed.)
+  void Arm();  // Arm  starting now.
+  void ArmSomeTimeDeltaAgo(const TimeDelta& time_delta);
+  void ArmAtStartTime(const TimeTicks start_time);
+
+  // Reset time, and do not set off the alarm.
+  void Disarm();
+
+  // Alarm is called if the time expires after an Arm() without someone calling
+  // Disarm().  This method can be overridden to create testable classes.
+  virtual void Alarm();
+
+  // Reset static data to initial state. Useful for tests, to ensure
+  // they are independent.
+  static void ResetStaticData();
+
+ private:
+  class ThreadDelegate : public PlatformThread::Delegate {
+   public:
+    explicit ThreadDelegate(Watchdog* watchdog) : watchdog_(watchdog) {
+    }
+    virtual void ThreadMain() OVERRIDE;
+   private:
+    void SetThreadName() const;
+
+    Watchdog* watchdog_;
+  };
+
+  enum State {ARMED, DISARMED, SHUTDOWN, JOINABLE };
+
+  bool enabled_;
+
+  Lock lock_;  // Mutex for state_.
+  ConditionVariable condition_variable_;
+  State state_;
+  const TimeDelta duration_;  // How long after start_time_ do we alarm?
+  const std::string thread_watched_name_;
+  PlatformThreadHandle handle_;
+  ThreadDelegate delegate_;  // Store it, because it must outlive the thread.
+
+  TimeTicks start_time_;  // Start of epoch, and alarm after duration_.
+
+  DISALLOW_COPY_AND_ASSIGN(Watchdog);
+};
+
+}  // namespace base
+
+#endif  // BASE_THREADING_WATCHDOG_H_
diff --git a/chromium/base/threading/watchdog_unittest.cc b/chromium/base/threading/watchdog_unittest.cc
new file mode 100644
index 00000000000..7a4be4c764c
--- /dev/null
+++ b/chromium/base/threading/watchdog_unittest.cc
@@ -0,0 +1,142 @@
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "base/threading/watchdog.h"
+
+#include "base/logging.h"
+#include "base/synchronization/spin_wait.h"
+#include "base/threading/platform_thread.h"
+#include "base/time/time.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace base {
+
+namespace {
+
+//------------------------------------------------------------------------------
+// Provide a derived class to facilitate testing.
+
+class WatchdogCounter : public Watchdog {
+ public:
+  WatchdogCounter(const TimeDelta& duration,
+                  const std::string& thread_watched_name,
+                  bool enabled)
+      : Watchdog(duration, thread_watched_name, enabled),
+        alarm_counter_(0) {
+  }
+
+  virtual ~WatchdogCounter() {}
+
+  virtual void Alarm() OVERRIDE {
+    alarm_counter_++;
+    Watchdog::Alarm();
+  }
+
+  int alarm_counter() { return alarm_counter_; }
+
+ private:
+  int alarm_counter_;
+
+  DISALLOW_COPY_AND_ASSIGN(WatchdogCounter);
+};
+
+class WatchdogTest : public testing::Test {
+ public:
+  virtual void SetUp() OVERRIDE {
+    Watchdog::ResetStaticData();
+  }
+};
+
+}  // namespace
+
+//------------------------------------------------------------------------------
+// Actual tests
+
+// Minimal constructor/destructor test.
+TEST_F(WatchdogTest, StartupShutdownTest) {
+  Watchdog watchdog1(TimeDelta::FromMilliseconds(300), "Disabled", false);
+  Watchdog watchdog2(TimeDelta::FromMilliseconds(300), "Enabled", true);
+}
+
+// Test ability to call Arm and Disarm repeatedly.
+TEST_F(WatchdogTest, ArmDisarmTest) {
+  Watchdog watchdog1(TimeDelta::FromMilliseconds(300), "Disabled", false);
+  watchdog1.Arm();
+  watchdog1.Disarm();
+  watchdog1.Arm();
+  watchdog1.Disarm();
+
+  Watchdog watchdog2(TimeDelta::FromMilliseconds(300), "Enabled", true);
+  watchdog2.Arm();
+  watchdog2.Disarm();
+  watchdog2.Arm();
+  watchdog2.Disarm();
+}
+
+// Make sure a basic alarm fires when the time has expired.
+TEST_F(WatchdogTest, AlarmTest) {
+  WatchdogCounter watchdog(TimeDelta::FromMilliseconds(10), "Enabled", true);
+  watchdog.Arm();
+  SPIN_FOR_TIMEDELTA_OR_UNTIL_TRUE(TimeDelta::FromMinutes(5),
+                                   watchdog.alarm_counter() > 0);
+  EXPECT_EQ(1, watchdog.alarm_counter());
+}
+
+// Make sure a basic alarm fires when the time has expired.
+TEST_F(WatchdogTest, AlarmPriorTimeTest) {
+  WatchdogCounter watchdog(TimeDelta(), "Enabled2", true);
+  // Set a time in the past.
+  watchdog.ArmSomeTimeDeltaAgo(TimeDelta::FromSeconds(2));
+  // It should instantly go off, but certainly in less than 5 minutes.
+  SPIN_FOR_TIMEDELTA_OR_UNTIL_TRUE(TimeDelta::FromMinutes(5),
+                                   watchdog.alarm_counter() > 0);
+
+  EXPECT_EQ(1, watchdog.alarm_counter());
+}
+
+// Make sure a disable alarm does nothing, even if we arm it.
+TEST_F(WatchdogTest, ConstructorDisabledTest) {
+  WatchdogCounter watchdog(TimeDelta::FromMilliseconds(10), "Disabled", false);
+  watchdog.Arm();
+  // Alarm should not fire, as it was disabled.
+  PlatformThread::Sleep(TimeDelta::FromMilliseconds(500));
+  EXPECT_EQ(0, watchdog.alarm_counter());
+}
+
+// Make sure Disarming will prevent firing, even after Arming.
+TEST_F(WatchdogTest, DisarmTest) {
+  WatchdogCounter watchdog(TimeDelta::FromSeconds(1), "Enabled3", true);
+
+  TimeTicks start = TimeTicks::Now();
+  watchdog.Arm();
+  // Sleep a bit, but not past the alarm point.
+  PlatformThread::Sleep(TimeDelta::FromMilliseconds(100));
+  watchdog.Disarm();
+  TimeTicks end = TimeTicks::Now();
+
+  if (end - start > TimeDelta::FromMilliseconds(500)) {
+    LOG(WARNING) << "100ms sleep took over 500ms, making the results of this "
+                 << "timing-sensitive test suspicious.  Aborting now.";
+    return;
+  }
+
+  // Alarm should not have fired before it was disarmed.
+  EXPECT_EQ(0, watchdog.alarm_counter());
+
+  // Sleep past the point where it would have fired if it wasn't disarmed,
+  // and verify that it didn't fire.
+  PlatformThread::Sleep(TimeDelta::FromSeconds(1));
+  EXPECT_EQ(0, watchdog.alarm_counter());
+
+  // ...but even after disarming, we can still use the alarm...
+  // Set a time greater than the timeout into the past.
+  watchdog.ArmSomeTimeDeltaAgo(TimeDelta::FromSeconds(10));
+  // It should almost instantly go off, but certainly in less than 5 minutes.
+  SPIN_FOR_TIMEDELTA_OR_UNTIL_TRUE(TimeDelta::FromMinutes(5),
+                                   watchdog.alarm_counter() > 0);
+
+  EXPECT_EQ(1, watchdog.alarm_counter());
+}
+
+}  // namespace base
diff --git a/chromium/base/threading/worker_pool.cc b/chromium/base/threading/worker_pool.cc
new file mode 100644
index 00000000000..9e45f8c89b8
--- /dev/null
+++ b/chromium/base/threading/worker_pool.cc
@@ -0,0 +1,117 @@
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "base/threading/worker_pool.h"
+
+#include "base/bind.h"
+#include "base/compiler_specific.h"
+#include "base/lazy_instance.h"
+#include "base/task_runner.h"
+#include "base/threading/post_task_and_reply_impl.h"
+#include "base/tracked_objects.h"
+
+namespace base {
+
+namespace {
+
+class PostTaskAndReplyWorkerPool : public internal::PostTaskAndReplyImpl {
+ public:
+  explicit PostTaskAndReplyWorkerPool(bool task_is_slow)
+      : task_is_slow_(task_is_slow) {
+  }
+
+ private:
+  virtual bool PostTask(const tracked_objects::Location& from_here,
+                        const Closure& task) OVERRIDE {
+    return WorkerPool::PostTask(from_here, task, task_is_slow_);
+  }
+
+  bool task_is_slow_;
+};
+
+// WorkerPoolTaskRunner ---------------------------------------------
+// A TaskRunner which posts tasks to a WorkerPool with a
+// fixed ShutdownBehavior.
+//
+// Note that this class is RefCountedThreadSafe (inherited from TaskRunner).
+class WorkerPoolTaskRunner : public TaskRunner {
+ public:
+  explicit WorkerPoolTaskRunner(bool tasks_are_slow);
+
+  // TaskRunner implementation
+  virtual bool PostDelayedTask(const tracked_objects::Location& from_here,
+                               const Closure& task,
+                               TimeDelta delay) OVERRIDE;
+  virtual bool RunsTasksOnCurrentThread() const OVERRIDE;
+
+ private:
+  virtual ~WorkerPoolTaskRunner();
+
+  // Helper function for posting a delayed task. Asserts that the delay is
+  // zero because non-zero delays are not supported.
+  bool PostDelayedTaskAssertZeroDelay(
+      const tracked_objects::Location& from_here,
+      const Closure& task,
+      base::TimeDelta delay);
+
+  const bool tasks_are_slow_;
+
+  DISALLOW_COPY_AND_ASSIGN(WorkerPoolTaskRunner);
+};
+
+WorkerPoolTaskRunner::WorkerPoolTaskRunner(bool tasks_are_slow)
+    : tasks_are_slow_(tasks_are_slow) {
+}
+
+WorkerPoolTaskRunner::~WorkerPoolTaskRunner() {
+}
+
+bool WorkerPoolTaskRunner::PostDelayedTask(
+    const tracked_objects::Location& from_here,
+    const Closure& task,
+    TimeDelta delay) {
+  return PostDelayedTaskAssertZeroDelay(from_here, task, delay);
+}
+
+bool WorkerPoolTaskRunner::RunsTasksOnCurrentThread() const {
+  return WorkerPool::RunsTasksOnCurrentThread();
+}
+
+bool WorkerPoolTaskRunner::PostDelayedTaskAssertZeroDelay(
+    const tracked_objects::Location& from_here,
+    const Closure& task,
+    base::TimeDelta delay) {
+  DCHECK_EQ(delay.InMillisecondsRoundedUp(), 0)
+      << "WorkerPoolTaskRunner does not support non-zero delays";
+  return WorkerPool::PostTask(from_here, task, tasks_are_slow_);
+}
+
+struct TaskRunnerHolder {
+  TaskRunnerHolder() {
+    taskrunners_[0] = new WorkerPoolTaskRunner(false);
+    taskrunners_[1] = new WorkerPoolTaskRunner(true);
+  }
+  scoped_refptr<TaskRunner> taskrunners_[2];
+};
+
+base::LazyInstance<TaskRunnerHolder>::Leaky
+    g_taskrunners = LAZY_INSTANCE_INITIALIZER;
+
+}  // namespace
+
+bool WorkerPool::PostTaskAndReply(const tracked_objects::Location& from_here,
+                                  const Closure& task,
+                                  const Closure& reply,
+                                  bool task_is_slow) {
+  return PostTaskAndReplyWorkerPool(task_is_slow).PostTaskAndReply(
+      from_here, task, reply);
+}
+
+// static
+const scoped_refptr<TaskRunner>&
+WorkerPool::GetTaskRunner(bool tasks_are_slow) {
+  return g_taskrunners.Get().taskrunners_[tasks_are_slow];
+}
+
+}  // namespace base
diff --git a/chromium/base/threading/worker_pool.h b/chromium/base/threading/worker_pool.h
new file mode 100644
index 00000000000..333b4950f6b
--- /dev/null
+++ b/chromium/base/threading/worker_pool.h
@@ -0,0 +1,60 @@
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef BASE_THREADING_WORKER_POOL_H_
+#define BASE_THREADING_WORKER_POOL_H_
+
+#include "base/base_export.h"
+#include "base/callback_forward.h"
+#include "base/memory/ref_counted.h"
+
+class Task;
+
+namespace tracked_objects {
+class Location;
+}  // namespace tracked_objects
+
+namespace base {
+
+class TaskRunner;
+
+// This is a facility that runs tasks that don't require a specific thread or
+// a message loop.
+//
+// WARNING: This shouldn't be used unless absolutely necessary. We don't wait
+// for the worker pool threads to finish on shutdown, so the tasks running
+// inside the pool must be extremely careful about other objects they access
+// (MessageLoops, Singletons, etc). During shutdown these object may no longer
+// exist.
+class BASE_EXPORT WorkerPool {
+ public:
+  // This function posts |task| to run on a worker thread.  |task_is_slow|
+  // should be used for tasks that will take a long time to execute.  Returns
+  // false if |task| could not be posted to a worker thread.  Regardless of
+  // return value, ownership of |task| is transferred to the worker pool.
+  static bool PostTask(const tracked_objects::Location& from_here,
+                       const base::Closure& task, bool task_is_slow);
+
+  // Just like MessageLoopProxy::PostTaskAndReply, except the destination
+  // for |task| is a worker thread and you can specify |task_is_slow| just
+  // like you can for PostTask above.
+  static bool PostTaskAndReply(const tracked_objects::Location& from_here,
+                               const Closure& task,
+                               const Closure& reply,
+                               bool task_is_slow);
+
+  // Return true if the current thread is one that this WorkerPool runs tasks
+  // on.  (Note that if the Windows worker pool is used without going through
+  // this WorkerPool interface, RunsTasksOnCurrentThread would return false on
+  // those threads.)
+  static bool RunsTasksOnCurrentThread();
+
+  // Get a TaskRunner wrapper which posts to the WorkerPool using the given
+  // |task_is_slow| behavior.
+  static const scoped_refptr<TaskRunner>& GetTaskRunner(bool task_is_slow);
+};
+
+}  // namespace base
+
+#endif  // BASE_THREADING_WORKER_POOL_H_
diff --git a/chromium/base/threading/worker_pool_posix.cc b/chromium/base/threading/worker_pool_posix.cc
new file mode 100644
index 00000000000..c4c523f270d
--- /dev/null
+++ b/chromium/base/threading/worker_pool_posix.cc
@@ -0,0 +1,202 @@
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "base/threading/worker_pool_posix.h"
+
+#include "base/bind.h"
+#include "base/callback.h"
+#include "base/debug/trace_event.h"
+#include "base/lazy_instance.h"
+#include "base/logging.h"
+#include "base/memory/ref_counted.h"
+#include "base/strings/stringprintf.h"
+#include "base/threading/platform_thread.h"
+#include "base/threading/thread_local.h"
+#include "base/threading/worker_pool.h"
+#include "base/tracked_objects.h"
+
+using tracked_objects::TrackedTime;
+
+namespace base {
+
+namespace {
+
+base::LazyInstance<ThreadLocalBoolean>::Leaky
+    g_worker_pool_running_on_this_thread = LAZY_INSTANCE_INITIALIZER;
+
+const int kIdleSecondsBeforeExit = 10 * 60;
+
+#ifdef ADDRESS_SANITIZER
+const int kWorkerThreadStackSize = 256 * 1024;
+#else
+// A stack size of 64 KB is too small for the CERT_PKIXVerifyCert
+// function of NSS because of NSS bug 439169.
+const int kWorkerThreadStackSize = 128 * 1024;
+#endif
+
+class WorkerPoolImpl {
+ public:
+  WorkerPoolImpl();
+  ~WorkerPoolImpl();
+
+  void PostTask(const tracked_objects::Location& from_here,
+                const base::Closure& task, bool task_is_slow);
+
+ private:
+  scoped_refptr<base::PosixDynamicThreadPool> pool_;
+};
+
+WorkerPoolImpl::WorkerPoolImpl()
+    : pool_(new base::PosixDynamicThreadPool("WorkerPool",
+                                             kIdleSecondsBeforeExit)) {
+}
+
+WorkerPoolImpl::~WorkerPoolImpl() {
+  pool_->Terminate();
+}
+
+void WorkerPoolImpl::PostTask(const tracked_objects::Location& from_here,
+                              const base::Closure& task, bool task_is_slow) {
+  pool_->PostTask(from_here, task);
+}
+
+base::LazyInstance<WorkerPoolImpl> g_lazy_worker_pool =
+    LAZY_INSTANCE_INITIALIZER;
+
+class WorkerThread : public PlatformThread::Delegate {
+ public:
+  WorkerThread(const std::string& name_prefix,
+               base::PosixDynamicThreadPool* pool)
+      : name_prefix_(name_prefix),
+        pool_(pool) {}
+
+  virtual void ThreadMain() OVERRIDE;
+
+ private:
+  const std::string name_prefix_;
+  scoped_refptr<base::PosixDynamicThreadPool> pool_;
+
+  DISALLOW_COPY_AND_ASSIGN(WorkerThread);
+};
+
+void WorkerThread::ThreadMain() {
+  g_worker_pool_running_on_this_thread.Get().Set(true);
+  const std::string name = base::StringPrintf(
+      "%s/%d", name_prefix_.c_str(), PlatformThread::CurrentId());
+  // Note |name.c_str()| must remain valid for for the whole life of the thread.
+  PlatformThread::SetName(name.c_str());
+
+  for (;;) {
+    PendingTask pending_task = pool_->WaitForTask();
+    if (pending_task.task.is_null())
+      break;
+    TRACE_EVENT2("task", "WorkerThread::ThreadMain::Run",
+        "src_file", pending_task.posted_from.file_name(),
+        "src_func", pending_task.posted_from.function_name());
+
+    TrackedTime start_time =
+        tracked_objects::ThreadData::NowForStartOfRun(pending_task.birth_tally);
+
+    pending_task.task.Run();
+
+    tracked_objects::ThreadData::TallyRunOnWorkerThreadIfTracking(
+        pending_task.birth_tally, TrackedTime(pending_task.time_posted),
+        start_time, tracked_objects::ThreadData::NowForEndOfRun());
+  }
+
+  // The WorkerThread is non-joinable, so it deletes itself.
+  delete this;
+}
+
+}  // namespace
+
+// static
+bool WorkerPool::PostTask(const tracked_objects::Location& from_here,
+                          const base::Closure& task, bool task_is_slow) {
+  g_lazy_worker_pool.Pointer()->PostTask(from_here, task, task_is_slow);
+  return true;
+}
+
+// static
+bool WorkerPool::RunsTasksOnCurrentThread() {
+  return g_worker_pool_running_on_this_thread.Get().Get();
+}
+
+PosixDynamicThreadPool::PosixDynamicThreadPool(const std::string& name_prefix,
+                                               int idle_seconds_before_exit)
+    : name_prefix_(name_prefix),
+      idle_seconds_before_exit_(idle_seconds_before_exit),
+      pending_tasks_available_cv_(&lock_),
+      num_idle_threads_(0),
+      terminated_(false) {}
+
+PosixDynamicThreadPool::~PosixDynamicThreadPool() {
+  while (!pending_tasks_.empty())
+    pending_tasks_.pop();
+}
+
+void PosixDynamicThreadPool::Terminate() {
+  {
+    AutoLock locked(lock_);
+    DCHECK(!terminated_) << "Thread pool is already terminated.";
+    terminated_ = true;
+  }
+  pending_tasks_available_cv_.Broadcast();
+}
+
+void PosixDynamicThreadPool::PostTask(
+    const tracked_objects::Location& from_here,
+    const base::Closure& task) {
+  PendingTask pending_task(from_here, task);
+  AddTask(&pending_task);
+}
+
+void PosixDynamicThreadPool::AddTask(PendingTask* pending_task) {
+  AutoLock locked(lock_);
+  DCHECK(!terminated_) <<
+      "This thread pool is already terminated.  Do not post new tasks.";
+
+  pending_tasks_.push(*pending_task);
+  pending_task->task.Reset();
+
+  // We have enough worker threads.
+  if (static_cast<size_t>(num_idle_threads_) >= pending_tasks_.size()) {
+    pending_tasks_available_cv_.Signal();
+  } else {
+    // The new PlatformThread will take ownership of the WorkerThread object,
+    // which will delete itself on exit.
+    WorkerThread* worker =
+        new WorkerThread(name_prefix_, this);
+    PlatformThread::CreateNonJoinable(kWorkerThreadStackSize, worker);
+  }
+}
+
+PendingTask PosixDynamicThreadPool::WaitForTask() {
+  AutoLock locked(lock_);
+
+  if (terminated_)
+    return PendingTask(FROM_HERE, base::Closure());
+
+  if (pending_tasks_.empty()) {  // No work available, wait for work.
+    num_idle_threads_++;
+    if (num_idle_threads_cv_.get())
+      num_idle_threads_cv_->Signal();
+    pending_tasks_available_cv_.TimedWait(
+        TimeDelta::FromSeconds(idle_seconds_before_exit_));
+    num_idle_threads_--;
+    if (num_idle_threads_cv_.get())
+      num_idle_threads_cv_->Signal();
+    if (pending_tasks_.empty()) {
+      // We waited for work, but there's still no work.  Return NULL to signal
+      // the thread to terminate.
+      return PendingTask(FROM_HERE, base::Closure());
+    }
+  }
+
+  PendingTask pending_task = pending_tasks_.front();
+  pending_tasks_.pop();
+  return pending_task;
+}
+
+}  // namespace base
diff --git a/chromium/base/threading/worker_pool_posix.h b/chromium/base/threading/worker_pool_posix.h
new file mode 100644
index 00000000000..dd0ffb656fa
--- /dev/null
+++ b/chromium/base/threading/worker_pool_posix.h
@@ -0,0 +1,98 @@
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+//
+// The thread pool used in the POSIX implementation of WorkerPool dynamically
+// adds threads as necessary to handle all tasks.  It keeps old threads around
+// for a period of time to allow them to be reused.  After this waiting period,
+// the threads exit.  This thread pool uses non-joinable threads, therefore
+// worker threads are not joined during process shutdown.  This means that
+// potentially long running tasks (such as DNS lookup) do not block process
+// shutdown, but also means that process shutdown may "leak" objects.  Note that
+// although PosixDynamicThreadPool spawns the worker threads and manages the
+// task queue, it does not own the worker threads.  The worker threads ask the
+// PosixDynamicThreadPool for work and eventually clean themselves up.  The
+// worker threads all maintain scoped_refptrs to the PosixDynamicThreadPool
+// instance, which prevents PosixDynamicThreadPool from disappearing before all
+// worker threads exit.  The owner of PosixDynamicThreadPool should likewise
+// maintain a scoped_refptr to the PosixDynamicThreadPool instance.
+//
+// NOTE: The classes defined in this file are only meant for use by the POSIX
+// implementation of WorkerPool.  No one else should be using these classes.
+// These symbols are exported in a header purely for testing purposes.
+
+#ifndef BASE_THREADING_WORKER_POOL_POSIX_H_
+#define BASE_THREADING_WORKER_POOL_POSIX_H_
+
+#include <queue>
+#include <string>
+
+#include "base/basictypes.h"
+#include "base/callback_forward.h"
+#include "base/location.h"
+#include "base/memory/ref_counted.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/pending_task.h"
+#include "base/synchronization/condition_variable.h"
+#include "base/synchronization/lock.h"
+#include "base/threading/platform_thread.h"
+#include "base/tracked_objects.h"
+
+class Task;
+
+namespace base {
+
+class BASE_EXPORT PosixDynamicThreadPool
+    : public RefCountedThreadSafe<PosixDynamicThreadPool> {
+ public:
+  class PosixDynamicThreadPoolPeer;
+
+  // All worker threads will share the same |name_prefix|.  They will exit after
+  // |idle_seconds_before_exit|.
+  PosixDynamicThreadPool(const std::string& name_prefix,
+                         int idle_seconds_before_exit);
+
+  // Indicates that the thread pool is going away.  Stops handing out tasks to
+  // worker threads.  Wakes up all the idle threads to let them exit.
+  void Terminate();
+
+  // Adds |task| to the thread pool.
+  void PostTask(const tracked_objects::Location& from_here,
+                const Closure& task);
+
+  // Worker thread method to wait for up to |idle_seconds_before_exit| for more
+  // work from the thread pool.  Returns NULL if no work is available.
+  PendingTask WaitForTask();
+
+ private:
+  friend class RefCountedThreadSafe<PosixDynamicThreadPool>;
+  friend class PosixDynamicThreadPoolPeer;
+
+  ~PosixDynamicThreadPool();
+
+  // Adds pending_task to the thread pool.  This function will clear
+  // |pending_task->task|.
+  void AddTask(PendingTask* pending_task);
+
+  const std::string name_prefix_;
+  const int idle_seconds_before_exit_;
+
+  Lock lock_;  // Protects all the variables below.
+
+  // Signal()s worker threads to let them know more tasks are available.
+  // Also used for Broadcast()'ing to worker threads to let them know the pool
+  // is being deleted and they can exit.
+  ConditionVariable pending_tasks_available_cv_;
+  int num_idle_threads_;
+  TaskQueue pending_tasks_;
+  bool terminated_;
+  // Only used for tests to ensure correct thread ordering.  It will always be
+  // NULL in non-test code.
+  scoped_ptr<ConditionVariable> num_idle_threads_cv_;
+
+  DISALLOW_COPY_AND_ASSIGN(PosixDynamicThreadPool);
+};
+
+}  // namespace base
+
+#endif  // BASE_THREADING_WORKER_POOL_POSIX_H_
diff --git a/chromium/base/threading/worker_pool_posix_unittest.cc b/chromium/base/threading/worker_pool_posix_unittest.cc
new file mode 100644
index 00000000000..49f6570aa4e
--- /dev/null
+++ b/chromium/base/threading/worker_pool_posix_unittest.cc
@@ -0,0 +1,254 @@
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "base/threading/worker_pool_posix.h"
+
+#include <set>
+
+#include "base/bind.h"
+#include "base/callback.h"
+#include "base/synchronization/condition_variable.h"
+#include "base/synchronization/lock.h"
+#include "base/threading/platform_thread.h"
+#include "base/synchronization/waitable_event.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace base {
+
+// Peer class to provide passthrough access to PosixDynamicThreadPool internals.
+class PosixDynamicThreadPool::PosixDynamicThreadPoolPeer {
+ public:
+  explicit PosixDynamicThreadPoolPeer(PosixDynamicThreadPool* pool)
+      : pool_(pool) {}
+
+  Lock* lock() { return &pool_->lock_; }
+  ConditionVariable* pending_tasks_available_cv() {
+    return &pool_->pending_tasks_available_cv_;
+  }
+  const std::queue<PendingTask>& pending_tasks() const {
+    return pool_->pending_tasks_;
+  }
+  int num_idle_threads() const { return pool_->num_idle_threads_; }
+  ConditionVariable* num_idle_threads_cv() {
+    return pool_->num_idle_threads_cv_.get();
+  }
+  void set_num_idle_threads_cv(ConditionVariable* cv) {
+    pool_->num_idle_threads_cv_.reset(cv);
+  }
+
+ private:
+  PosixDynamicThreadPool* pool_;
+
+  DISALLOW_COPY_AND_ASSIGN(PosixDynamicThreadPoolPeer);
+};
+
+namespace {
+
+// IncrementingTask's main purpose is to increment a counter.  It also updates a
+// set of unique thread ids, and signals a ConditionVariable on completion.
+// Note that since it does not block, there is no way to control the number of
+// threads used if more than one IncrementingTask is consecutively posted to the
+// thread pool, since the first one might finish executing before the subsequent
+// PostTask() calls get invoked.
+void IncrementingTask(Lock* counter_lock,
+                      int* counter,
+                      Lock* unique_threads_lock,
+                      std::set<PlatformThreadId>* unique_threads) {
+  {
+    base::AutoLock locked(*unique_threads_lock);
+    unique_threads->insert(PlatformThread::CurrentId());
+  }
+  base::AutoLock locked(*counter_lock);
+  (*counter)++;
+}
+
+// BlockingIncrementingTask is a simple wrapper around IncrementingTask that
+// allows for waiting at the start of Run() for a WaitableEvent to be signalled.
+struct BlockingIncrementingTaskArgs {
+  Lock* counter_lock;
+  int* counter;
+  Lock* unique_threads_lock;
+  std::set<PlatformThreadId>* unique_threads;
+  Lock* num_waiting_to_start_lock;
+  int* num_waiting_to_start;
+  ConditionVariable* num_waiting_to_start_cv;
+  base::WaitableEvent* start;
+};
+
+void BlockingIncrementingTask(const BlockingIncrementingTaskArgs& args) {
+  {
+    base::AutoLock num_waiting_to_start_locked(*args.num_waiting_to_start_lock);
+    (*args.num_waiting_to_start)++;
+  }
+  args.num_waiting_to_start_cv->Signal();
+  args.start->Wait();
+  IncrementingTask(args.counter_lock, args.counter, args.unique_threads_lock,
+                   args.unique_threads);
+}
+
+class PosixDynamicThreadPoolTest : public testing::Test {
+ protected:
+  PosixDynamicThreadPoolTest()
+      : pool_(new base::PosixDynamicThreadPool("dynamic_pool", 60*60)),
+        peer_(pool_.get()),
+        counter_(0),
+        num_waiting_to_start_(0),
+        num_waiting_to_start_cv_(&num_waiting_to_start_lock_),
+        start_(true, false) {}
+
+  virtual void SetUp() OVERRIDE {
+    peer_.set_num_idle_threads_cv(new ConditionVariable(peer_.lock()));
+  }
+
+  virtual void TearDown() OVERRIDE {
+    // Wake up the idle threads so they can terminate.
+    if (pool_.get()) pool_->Terminate();
+  }
+
+  void WaitForTasksToStart(int num_tasks) {
+    base::AutoLock num_waiting_to_start_locked(num_waiting_to_start_lock_);
+    while (num_waiting_to_start_ < num_tasks) {
+      num_waiting_to_start_cv_.Wait();
+    }
+  }
+
+  void WaitForIdleThreads(int num_idle_threads) {
+    base::AutoLock pool_locked(*peer_.lock());
+    while (peer_.num_idle_threads() < num_idle_threads) {
+      peer_.num_idle_threads_cv()->Wait();
+    }
+  }
+
+  base::Closure CreateNewIncrementingTaskCallback() {
+    return base::Bind(&IncrementingTask, &counter_lock_, &counter_,
+                      &unique_threads_lock_, &unique_threads_);
+  }
+
+  base::Closure CreateNewBlockingIncrementingTaskCallback() {
+    BlockingIncrementingTaskArgs args = {
+        &counter_lock_, &counter_, &unique_threads_lock_, &unique_threads_,
+        &num_waiting_to_start_lock_, &num_waiting_to_start_,
+        &num_waiting_to_start_cv_, &start_
+    };
+    return base::Bind(&BlockingIncrementingTask, args);
+  }
+
+  scoped_refptr<base::PosixDynamicThreadPool> pool_;
+  base::PosixDynamicThreadPool::PosixDynamicThreadPoolPeer peer_;
+  Lock counter_lock_;
+  int counter_;
+  Lock unique_threads_lock_;
+  std::set<PlatformThreadId> unique_threads_;
+  Lock num_waiting_to_start_lock_;
+  int num_waiting_to_start_;
+  ConditionVariable num_waiting_to_start_cv_;
+  base::WaitableEvent start_;
+};
+
+}  // namespace
+
+TEST_F(PosixDynamicThreadPoolTest, Basic) {
+  EXPECT_EQ(0, peer_.num_idle_threads());
+  EXPECT_EQ(0U, unique_threads_.size());
+  EXPECT_EQ(0U, peer_.pending_tasks().size());
+
+  // Add one task and wait for it to be completed.
+  pool_->PostTask(FROM_HERE, CreateNewIncrementingTaskCallback());
+
+  WaitForIdleThreads(1);
+
+  EXPECT_EQ(1U, unique_threads_.size()) <<
+      "There should be only one thread allocated for one task.";
+  EXPECT_EQ(1, peer_.num_idle_threads());
+  EXPECT_EQ(1, counter_);
+}
+
+TEST_F(PosixDynamicThreadPoolTest, ReuseIdle) {
+  // Add one task and wait for it to be completed.
+  pool_->PostTask(FROM_HERE, CreateNewIncrementingTaskCallback());
+
+  WaitForIdleThreads(1);
+
+  // Add another 2 tasks.  One should reuse the existing worker thread.
+  pool_->PostTask(FROM_HERE, CreateNewBlockingIncrementingTaskCallback());
+  pool_->PostTask(FROM_HERE, CreateNewBlockingIncrementingTaskCallback());
+
+  WaitForTasksToStart(2);
+  start_.Signal();
+  WaitForIdleThreads(2);
+
+  EXPECT_EQ(2U, unique_threads_.size());
+  EXPECT_EQ(2, peer_.num_idle_threads());
+  EXPECT_EQ(3, counter_);
+}
+
+TEST_F(PosixDynamicThreadPoolTest, TwoActiveTasks) {
+  // Add two blocking tasks.
+  pool_->PostTask(FROM_HERE, CreateNewBlockingIncrementingTaskCallback());
+  pool_->PostTask(FROM_HERE, CreateNewBlockingIncrementingTaskCallback());
+
+  EXPECT_EQ(0, counter_) << "Blocking tasks should not have started yet.";
+
+  WaitForTasksToStart(2);
+  start_.Signal();
+  WaitForIdleThreads(2);
+
+  EXPECT_EQ(2U, unique_threads_.size());
+  EXPECT_EQ(2, peer_.num_idle_threads()) << "Existing threads are now idle.";
+  EXPECT_EQ(2, counter_);
+}
+
+TEST_F(PosixDynamicThreadPoolTest, Complex) {
+  // Add two non blocking tasks and wait for them to finish.
+  pool_->PostTask(FROM_HERE, CreateNewIncrementingTaskCallback());
+
+  WaitForIdleThreads(1);
+
+  // Add two blocking tasks, start them simultaneously, and wait for them to
+  // finish.
+  pool_->PostTask(FROM_HERE, CreateNewBlockingIncrementingTaskCallback());
+  pool_->PostTask(FROM_HERE, CreateNewBlockingIncrementingTaskCallback());
+
+  WaitForTasksToStart(2);
+  start_.Signal();
+  WaitForIdleThreads(2);
+
+  EXPECT_EQ(3, counter_);
+  EXPECT_EQ(2, peer_.num_idle_threads());
+  EXPECT_EQ(2U, unique_threads_.size());
+
+  // Wake up all idle threads so they can exit.
+  {
+    base::AutoLock locked(*peer_.lock());
+    while (peer_.num_idle_threads() > 0) {
+      peer_.pending_tasks_available_cv()->Signal();
+      peer_.num_idle_threads_cv()->Wait();
+    }
+  }
+
+  // Add another non blocking task.  There are no threads to reuse.
+  pool_->PostTask(FROM_HERE, CreateNewIncrementingTaskCallback());
+  WaitForIdleThreads(1);
+
+  // The POSIX implementation of PlatformThread::CurrentId() uses pthread_self()
+  // which is not guaranteed to be unique after a thread joins. The OS X
+  // implemntation of pthread_self() returns the address of the pthread_t, which
+  // is merely a malloc()ed pointer stored in the first TLS slot. When a thread
+  // joins and that structure is freed, the block of memory can be put on the
+  // OS free list, meaning the same address could be reused in a subsequent
+  // allocation. This in fact happens when allocating in a loop as this test
+  // does.
+  //
+  // Because there are two concurrent threads, there's at least the guarantee
+  // of having two unique thread IDs in the set. But after those two threads are
+  // joined, the next-created thread can get a re-used ID if the allocation of
+  // the pthread_t structure is taken from the free list. Therefore, there can
+  // be either 2 or 3 unique thread IDs in the set at this stage in the test.
+  EXPECT_TRUE(unique_threads_.size() >= 2 && unique_threads_.size() <= 3)
+      << "unique_threads_.size() = " << unique_threads_.size();
+  EXPECT_EQ(1, peer_.num_idle_threads());
+  EXPECT_EQ(4, counter_);
+}
+
+}  // namespace base
diff --git a/chromium/base/threading/worker_pool_unittest.cc b/chromium/base/threading/worker_pool_unittest.cc
new file mode 100644
index 00000000000..9a9ab951b9e
--- /dev/null
+++ b/chromium/base/threading/worker_pool_unittest.cc
@@ -0,0 +1,112 @@
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "base/threading/worker_pool.h"
+
+#include "base/bind.h"
+#include "base/bind_helpers.h"
+#include "base/location.h"
+#include "base/message_loop/message_loop.h"
+#include "base/run_loop.h"
+#include "base/synchronization/waitable_event.h"
+#include "base/test/test_timeouts.h"
+#include "base/threading/thread_checker_impl.h"
+#include "base/time/time.h"
+#include "testing/gtest/include/gtest/gtest.h"
+#include "testing/platform_test.h"
+
+typedef PlatformTest WorkerPoolTest;
+
+namespace base {
+
+namespace {
+
+class PostTaskAndReplyTester
+    : public base::RefCountedThreadSafe<PostTaskAndReplyTester> {
+ public:
+  PostTaskAndReplyTester() : finished_(false), test_event_(false, false) {}
+
+  void RunTest() {
+    ASSERT_TRUE(thread_checker_.CalledOnValidThread());
+    WorkerPool::PostTaskAndReply(
+      FROM_HERE,
+      base::Bind(&PostTaskAndReplyTester::OnWorkerThread, this),
+      base::Bind(&PostTaskAndReplyTester::OnOriginalThread, this),
+      false);
+
+    test_event_.Wait();
+  }
+
+  void OnWorkerThread() {
+    // We're not on the original thread.
+    EXPECT_FALSE(thread_checker_.CalledOnValidThread());
+
+    test_event_.Signal();
+  }
+
+  void OnOriginalThread() {
+    EXPECT_TRUE(thread_checker_.CalledOnValidThread());
+    finished_ = true;
+  }
+
+  bool finished() const {
+    return finished_;
+  }
+
+ private:
+  friend class base::RefCountedThreadSafe<PostTaskAndReplyTester>;
+  ~PostTaskAndReplyTester() {}
+
+  bool finished_;
+  WaitableEvent test_event_;
+
+  // The Impl version performs its checks even in release builds.
+  ThreadCheckerImpl thread_checker_;
+};
+
+}  // namespace
+
+TEST_F(WorkerPoolTest, PostTask) {
+  WaitableEvent test_event(false, false);
+  WaitableEvent long_test_event(false, false);
+
+  WorkerPool::PostTask(FROM_HERE,
+                       base::Bind(&WaitableEvent::Signal,
+                                  base::Unretained(&test_event)),
+                       false);
+  WorkerPool::PostTask(FROM_HERE,
+                       base::Bind(&WaitableEvent::Signal,
+                                  base::Unretained(&long_test_event)),
+                       true);
+
+  test_event.Wait();
+  long_test_event.Wait();
+}
+
+#if defined(OS_WIN) || defined(OS_LINUX)
+// Flaky on Windows and Linux (http://crbug.com/130337)
+#define MAYBE_PostTaskAndReply DISABLED_PostTaskAndReply
+#else
+#define MAYBE_PostTaskAndReply PostTaskAndReply
+#endif
+
+TEST_F(WorkerPoolTest, MAYBE_PostTaskAndReply) {
+  MessageLoop message_loop;
+  scoped_refptr<PostTaskAndReplyTester> tester(new PostTaskAndReplyTester());
+  tester->RunTest();
+
+  const TimeDelta kMaxDuration = TestTimeouts::tiny_timeout();
+  TimeTicks start = TimeTicks::Now();
+  while (!tester->finished() && TimeTicks::Now() - start < kMaxDuration) {
+#if defined(OS_IOS)
+    // Ensure that the other thread has a chance to run even on a single-core
+    // device.
+    pthread_yield_np();
+#endif
+    RunLoop().RunUntilIdle();
+  }
+  EXPECT_TRUE(tester->finished());
+}
+
+}  // namespace base
diff --git a/chromium/base/threading/worker_pool_win.cc b/chromium/base/threading/worker_pool_win.cc
new file mode 100644
index 00000000000..c27010fb12f
--- /dev/null
+++ b/chromium/base/threading/worker_pool_win.cc
@@ -0,0 +1,73 @@
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "base/threading/worker_pool.h"
+
+#include "base/bind.h"
+#include "base/callback.h"
+#include "base/debug/trace_event.h"
+#include "base/logging.h"
+#include "base/pending_task.h"
+#include "base/threading/thread_local.h"
+#include "base/tracked_objects.h"
+
+namespace base {
+
+namespace {
+
+base::LazyInstance<ThreadLocalBoolean>::Leaky
+    g_worker_pool_running_on_this_thread = LAZY_INSTANCE_INITIALIZER;
+
+DWORD CALLBACK WorkItemCallback(void* param) {
+  PendingTask* pending_task = static_cast<PendingTask*>(param);
+  TRACE_EVENT2("task", "WorkItemCallback::Run",
+               "src_file", pending_task->posted_from.file_name(),
+               "src_func", pending_task->posted_from.function_name());
+
+  tracked_objects::TrackedTime start_time =
+      tracked_objects::ThreadData::NowForStartOfRun(pending_task->birth_tally);
+
+  g_worker_pool_running_on_this_thread.Get().Set(true);
+  pending_task->task.Run();
+  g_worker_pool_running_on_this_thread.Get().Set(false);
+
+  tracked_objects::ThreadData::TallyRunOnWorkerThreadIfTracking(
+      pending_task->birth_tally,
+      tracked_objects::TrackedTime(pending_task->time_posted), start_time,
+      tracked_objects::ThreadData::NowForEndOfRun());
+
+  delete pending_task;
+  return 0;
+}
+
+// Takes ownership of |pending_task|
+bool PostTaskInternal(PendingTask* pending_task, bool task_is_slow) {
+  ULONG flags = 0;
+  if (task_is_slow)
+    flags |= WT_EXECUTELONGFUNCTION;
+
+  if (!QueueUserWorkItem(WorkItemCallback, pending_task, flags)) {
+    DLOG_GETLASTERROR(ERROR) << "QueueUserWorkItem failed";
+    delete pending_task;
+    return false;
+  }
+
+  return true;
+}
+
+}  // namespace
+
+// static
+bool WorkerPool::PostTask(const tracked_objects::Location& from_here,
+                          const base::Closure& task, bool task_is_slow) {
+  PendingTask* pending_task = new PendingTask(from_here, task);
+  return PostTaskInternal(pending_task, task_is_slow);
+}
+
+// static
+bool WorkerPool::RunsTasksOnCurrentThread() {
+  return g_worker_pool_running_on_this_thread.Get().Get();
+}
+
+}  // namespace base