iwyu: Use callback_old.h where appropriate, part 2.

chrome/browser/tab_contents/thumbnail_generator.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_TAB_CONTENTS_THUMBNAIL_GENERATOR_H_
 #define CHROME_BROWSER_TAB_CONTENTS_THUMBNAIL_GENERATOR_H_
 #pragma once
 
 #include <map>
 #include <utility>
 #include <vector>
 
 #include "base/basictypes.h"
-#include "base/callback.h"
+#include "base/callback_old.h"
 #include "base/memory/linked_ptr.h"
 #include "base/timer.h"
 #include "content/browser/renderer_host/backing_store.h"
 #include "content/common/notification_observer.h"
 #include "content/common/notification_registrar.h"
 
 class GURL;
 class Profile;
 class RenderWidgetHost;
 class SkBitmap;
@@ skipping 121 matching lines @@
   typedef std::map<int,
                    linked_ptr<AsyncRequestInfo> > ThumbnailCallbackMap;
   ThumbnailCallbackMap callback_map_;
 
   TabContents* tab_contents_;
 
   DISALLOW_COPY_AND_ASSIGN(ThumbnailGenerator);
 };
 
 #endif  // CHROME_BROWSER_TAB_CONTENTS_THUMBNAIL_GENERATOR_H_