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

net/disk_cache/backend_impl.h

Index: net/disk_cache/backend_impl.h
===================================================================
--- net/disk_cache/backend_impl.h	(revision 126788)
+++ net/disk_cache/backend_impl.h	(working copy)
@@ -1,4 +1,4 @@
-// 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.
 
@@ -56,10 +56,10 @@
                            int max_bytes, net::CacheType type,
                            uint32 flags, base::MessageLoopProxy* thread,
                            net::NetLog* net_log, Backend** backend,
-                           const net::CompletionCallback& callback);
+                           const CompletionCallback& callback);
 
   // Performs general initialization for this current instance of the cache.
-  int Init(const net::CompletionCallback& callback);
+  int Init(const CompletionCallback& callback);
 
   // Performs the actual initialization and final cleanup on destruction.
   int SyncInit();
@@ -67,7 +67,7 @@
 
   // Same behavior as OpenNextEntry but walks the list from back to front.
   int OpenPrevEntry(void** iter, Entry** prev_entry,
-                    const net::CompletionCallback& callback);
+                    const CompletionCallback& callback);
 
   // Synchronous implementation of the asynchronous interface.
   int SyncOpenEntry(const std::string& key, Entry** entry);
@@ -100,9 +100,8 @@
   // Returns the actual file used to store a given (non-external) address.
   MappedFile* File(Addr address);
 
-  InFlightBackendIO* background_queue() {
-    return &background_queue_;
-  }
+  // Returns a weak pointer to the background queue.
+  base::WeakPtr<InFlightBackendIO> GetBackgroundQueue();
 
   // Creates an external storage file.
   bool CreateExternalFile(Addr* address);
@@ -238,12 +237,12 @@
   void ClearRefCountForTest();
 
   // Sends a dummy operation through the operation queue, for unit tests.
-  int FlushQueueForTest(const net::CompletionCallback& callback);
+  int FlushQueueForTest(const CompletionCallback& callback);
 
   // Runs the provided task on the cache thread. The task will be automatically
   // deleted after it runs.
   int RunTaskForTest(const base::Closure& task,
-                     const net::CompletionCallback& callback);
+                     const CompletionCallback& callback);
 
   // Trims an entry (all if |empty| is true) from the list of deleted
   // entries. This method should be called directly on the cache thread.
@@ -260,21 +259,19 @@
   // Backend implementation.
   virtual int32 GetEntryCount() const OVERRIDE;
   virtual int OpenEntry(const std::string& key, Entry** entry,
-                        const net::CompletionCallback& callback) OVERRIDE;
+                        const CompletionCallback& callback) OVERRIDE;
   virtual int CreateEntry(const std::string& key, Entry** entry,
-                          const net::CompletionCallback& callback) OVERRIDE;
+                          const CompletionCallback& callback) OVERRIDE;
   virtual int DoomEntry(const std::string& key,
-                        const net::CompletionCallback& callback) OVERRIDE;
-  virtual int DoomAllEntries(const net::CompletionCallback& callback) OVERRIDE;
-  virtual int DoomEntriesBetween(
-      const base::Time initial_time,
-      const base::Time end_time,
-      const net::CompletionCallback& callback) OVERRIDE;
-  virtual int DoomEntriesSince(
-      const base::Time initial_time,
-      const net::CompletionCallback& callback) OVERRIDE;
+                        const CompletionCallback& callback) OVERRIDE;
+  virtual int DoomAllEntries(const CompletionCallback& callback) OVERRIDE;
+  virtual int DoomEntriesBetween(const base::Time initial_time,
+                                 const base::Time end_time,
+                                 const CompletionCallback& callback) OVERRIDE;
+  virtual int DoomEntriesSince(const base::Time initial_time,
+                               const CompletionCallback& callback) OVERRIDE;
   virtual int OpenNextEntry(void** iter, Entry** next_entry,
-                            const net::CompletionCallback& callback) OVERRIDE;
+                            const CompletionCallback& callback) OVERRIDE;
   virtual void EndEnumeration(void** iter) OVERRIDE;
   virtual void GetStats(StatsItems* stats) OVERRIDE;
   virtual void OnExternalCacheHit(const std::string& key) OVERRIDE;