Disk cache: Remove all non essential synchronization from the cache destructor.

net/disk_cache/storage_block.h

-// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// 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__
 #pragma once
 
 #include "net/disk_cache/addr.h"
@@ skipping 36 matching lines @@
   // 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.
@@ skipping 19 matching lines @@
 
   DISALLOW_COPY_AND_ASSIGN(StorageBlock);
 };
 
 typedef StorageBlock<EntryStore> CacheEntryBlock;
 typedef StorageBlock<RankingsNode> CacheRankingsBlock;
 
 }  // namespace disk_cache
 
 #endif  // NET_DISK_CACHE_STORAGE_BLOCK_H__