Cleanup: Remove unneeded forward declarations in chrome/browser/sync.

chrome/browser/sync/engine/apply_updates_command.h

-// Copyright (c) 2006-2009 The Chromium Authors. All rights reserved.
+// 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 CHROME_BROWSER_SYNC_ENGINE_APPLY_UPDATES_COMMAND_H_
 #define CHROME_BROWSER_SYNC_ENGINE_APPLY_UPDATES_COMMAND_H_
 #pragma once
 
 #include "chrome/browser/sync/engine/model_changing_syncer_command.h"
 
-namespace syncable {
-class WriteTransaction;
-class MutableEntry;
-class Id;
-}
-
 namespace browser_sync {
 
 class ApplyUpdatesCommand : public ModelChangingSyncerCommand {
  public:
   ApplyUpdatesCommand();
   virtual ~ApplyUpdatesCommand();
 
   // ModelChangingSyncerCommand implementation.
   virtual void ModelChangingExecuteImpl(sessions::SyncSession* session);
 
  private:
   DISALLOW_COPY_AND_ASSIGN(ApplyUpdatesCommand);
 };
 
 }  // namespace browser_sync
 
 #endif  // CHROME_BROWSER_SYNC_ENGINE_APPLY_UPDATES_COMMAND_H_