BASELINE: Update Chromium to 85.0.4183.14085-based

Change-Id: Iaa42f4680837c57725b1344f108c0196741f6057
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@qt.io>

1 files changed, 105 insertions, 7 deletions

diff --git a/chromium/v8/include/cppgc/platform.h b/chromium/v8/include/cppgc/platform.h
index 8dc5e14a7d6..72694c6ee13 100644
--- a/chromium/v8/include/cppgc/platform.h
+++ b/chromium/v8/include/cppgc/platform.h
@@ -10,16 +10,114 @@
 
 namespace cppgc {
 
-// TODO(v8:10346): Put PageAllocator in a non-V8 include header to avoid
-// depending on namespace v8.
+// TODO(v8:10346): Create separate includes for concepts that are not
+// V8-specific.
+using IdleTask = v8::IdleTask;
+using JobHandle = v8::JobHandle;
+using JobTask = v8::JobTask;
 using PageAllocator = v8::PageAllocator;
+using Task = v8::Task;
+using TaskPriority = v8::TaskPriority;
+using TaskRunner = v8::TaskRunner;
 
-// Initializes the garbage collector with the provided platform. Must be called
-// before creating a Heap.
-V8_EXPORT void InitializePlatform(PageAllocator* page_allocator);
+/**
+ * Platform interface used by Heap. Contains allocators and executors.
+ */
+class V8_EXPORT Platform {
+ public:
+  virtual ~Platform() = default;
 
-// Must be called after destroying the last used heap.
-V8_EXPORT void ShutdownPlatform();
+  /**
+   * Returns the allocator used by cppgc to allocate its heap and various
+   * support structures.
+   */
+  virtual PageAllocator* GetPageAllocator() = 0;
+
+  /**
+   * Monotonically increasing time in seconds from an arbitrary fixed point in
+   * the past. This function is expected to return at least
+   * millisecond-precision values. For this reason,
+   * it is recommended that the fixed point be no further in the past than
+   * the epoch.
+   **/
+  virtual double MonotonicallyIncreasingTime() = 0;
+
+  /**
+   * Foreground task runner that should be used by a Heap.
+   */
+  virtual std::shared_ptr<TaskRunner> GetForegroundTaskRunner() {
+    return nullptr;
+  }
+
+  /**
+   * Posts |job_task| to run in parallel. Returns a JobHandle associated with
+   * the Job, which can be joined or canceled.
+   * This avoids degenerate cases:
+   * - Calling CallOnWorkerThread() for each work item, causing significant
+   *   overhead.
+   * - Fixed number of CallOnWorkerThread() calls that split the work and might
+   *   run for a long time. This is problematic when many components post
+   *   "num cores" tasks and all expect to use all the cores. In these cases,
+   *   the scheduler lacks context to be fair to multiple same-priority requests
+   *   and/or ability to request lower priority work to yield when high priority
+   *   work comes in.
+   * A canonical implementation of |job_task| looks like:
+   * class MyJobTask : public JobTask {
+   *  public:
+   *   MyJobTask(...) : worker_queue_(...) {}
+   *   // JobTask:
+   *   void Run(JobDelegate* delegate) override {
+   *     while (!delegate->ShouldYield()) {
+   *       // Smallest unit of work.
+   *       auto work_item = worker_queue_.TakeWorkItem(); // Thread safe.
+   *       if (!work_item) return;
+   *       ProcessWork(work_item);
+   *     }
+   *   }
+   *
+   *   size_t GetMaxConcurrency() const override {
+   *     return worker_queue_.GetSize(); // Thread safe.
+   *   }
+   * };
+   * auto handle = PostJob(TaskPriority::kUserVisible,
+   *                       std::make_unique<MyJobTask>(...));
+   * handle->Join();
+   *
+   * PostJob() and methods of the returned JobHandle/JobDelegate, must never be
+   * called while holding a lock that could be acquired by JobTask::Run or
+   * JobTask::GetMaxConcurrency -- that could result in a deadlock. This is
+   * because [1] JobTask::GetMaxConcurrency may be invoked while holding
+   * internal lock (A), hence JobTask::GetMaxConcurrency can only use a lock (B)
+   * if that lock is *never* held while calling back into JobHandle from any
+   * thread (A=>B/B=>A deadlock) and [2] JobTask::Run or
+   * JobTask::GetMaxConcurrency may be invoked synchronously from JobHandle
+   * (B=>JobHandle::foo=>B deadlock).
+   *
+   * A sufficient PostJob() implementation that uses the default Job provided in
+   * libplatform looks like:
+   *  std::unique_ptr<JobHandle> PostJob(
+   *      TaskPriority priority, std::unique_ptr<JobTask> job_task) override {
+   *    return std::make_unique<DefaultJobHandle>(
+   *        std::make_shared<DefaultJobState>(
+   *            this, std::move(job_task), kNumThreads));
+   * }
+   */
+  virtual std::unique_ptr<JobHandle> PostJob(
+      TaskPriority priority, std::unique_ptr<JobTask> job_task) {
+    return nullptr;
+  }
+};
+
+/**
+ * Process-global initialization of the garbage collector. Must be called before
+ * creating a Heap.
+ */
+V8_EXPORT void InitializeProcess(PageAllocator*);
+
+/**
+ * Must be called after destroying the last used heap.
+ */
+V8_EXPORT void ShutdownProcess();
 
 namespace internal {