Use callback_forward.h instead of callback.h where possible.

chrome/browser/sync/glue/browser_thread_model_worker.h

 // 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_GLUE_BROWSER_THREAD_MODEL_WORKER_H_
 #define CHROME_BROWSER_SYNC_GLUE_BROWSER_THREAD_MODEL_WORKER_H_
 #pragma once
 
 #include "base/basictypes.h"
-#include "base/callback.h"
+#include "base/callback_forward.h"
 #include "base/compiler_specific.h"
 #include "chrome/browser/sync/engine/model_safe_worker.h"
 #include "chrome/browser/sync/util/unrecoverable_error_info.h"
 #include "content/public/browser/browser_thread.h"
 
 namespace base {
 class WaitableEvent;
 }
 
 namespace browser_sync {
@@ skipping 51 matching lines @@
  protected:
   virtual void CallDoWorkAndSignalTask(
       const WorkCallback& work,
       base::WaitableEvent* done,
       UnrecoverableErrorInfo* error_info) OVERRIDE;
 };
 
 }  // namespace browser_sync
 
 #endif  // CHROME_BROWSER_SYNC_GLUE_BROWSER_THREAD_MODEL_WORKER_H_