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diff --git a/chromium/net/disk_cache/storage_block.h b/chromium/net/disk_cache/storage_block.h
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+++ b/chromium/net/disk_cache/storage_block.h
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+// 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.
+
+// See net/disk_cache/disk_cache.h for the public interface.
+
+#ifndef NET_DISK_CACHE_STORAGE_BLOCK_H_
+#define NET_DISK_CACHE_STORAGE_BLOCK_H_
+
+#include "net/disk_cache/addr.h"
+#include "net/disk_cache/mapped_file.h"
+
+namespace disk_cache {
+
+// This class encapsulates common behavior of a single "block" of data that is
+// stored on a block-file. It implements the FileBlock interface, so it can be
+// serialized directly to the backing file.
+// This object provides a memory buffer for the related data, and it can be used
+// to actually share that memory with another instance of the class.
+//
+// The following example shows how to share storage with another object:
+//    StorageBlock<TypeA> a(file, address);
+//    StorageBlock<TypeB> b(file, address);
+//    a.Load();
+//    DoSomething(a.Data());
+//    b.SetData(a.Data());
+//    ModifySomething(b.Data());
+//    // Data modified on the previous call will be saved by b's destructor.
+//    b.set_modified();
+template<typename T>
+class StorageBlock : public FileBlock {
+ public:
+  StorageBlock(MappedFile* file, Addr address);
+  virtual ~StorageBlock();
+
+  // FileBlock interface.
+  virtual void* buffer() const;
+  virtual size_t size() const;
+  virtual int offset() const;
+
+  // Allows the overide of dummy values passed on the constructor.
+  bool LazyInit(MappedFile* file, Addr address);
+
+  // Sets the internal storage to share the memory provided by other instance.
+  void SetData(T* other);
+
+  // Deletes the data, even if it was modified and not saved. This object must
+  // own the memory buffer (it cannot be shared).
+  void Discard();
+
+  // Stops sharing the data with another object.
+  void StopSharingData();
+
+  // Sets the object to lazily save the in-memory data on destruction.
+  void set_modified();
+
+  // Forgets that the data was modified, so it's not lazily saved.
+  void clear_modified();
+
+  // Gets a pointer to the internal storage (allocates storage if needed).
+  T* Data();
+
+  // Returns true if there is data associated with this object.
+  bool HasData() const;
+
+  // Returns true if the internal hash is correct.
+  bool VerifyHash() const;
+
+  // Returns true if this object owns the data buffer, false if it is shared.
+  bool own_data() const;
+
+  const Addr address() const;
+
+  // Loads and store the data.
+  bool Load();
+  bool Store();
+
+ private:
+  void AllocateData();
+  void DeleteData();
+  uint32 CalculateHash() const;
+
+  T* data_;
+  MappedFile* file_;
+  Addr address_;
+  bool modified_;
+  bool own_data_;  // Is data_ owned by this object or shared with someone else.
+  bool extended_;  // Used to store an entry of more than one block.
+
+  DISALLOW_COPY_AND_ASSIGN(StorageBlock);
+};
+
+}  // namespace disk_cache
+
+#endif  // NET_DISK_CACHE_STORAGE_BLOCK_H_