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

chrome/browser/history/top_sites_backend.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_HISTORY_TOP_SITES_BACKEND_H_
 #define CHROME_BROWSER_HISTORY_TOP_SITES_BACKEND_H_
 #pragma once
 
+#include "base/callback_old.h"
 #include "base/file_path.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
 #include "chrome/browser/history/history_types.h"
 #include "content/browser/cancelable_request.h"
 
 class FilePath;
 
 namespace history {
 
@@ skipping 78 matching lines @@
   FilePath db_path_;
 
   scoped_ptr<TopSitesDatabase> db_;
 
   DISALLOW_COPY_AND_ASSIGN(TopSitesBackend);
 };
 
 }  // namespace history
 
 #endif  // CHROME_BROWSER_HISTORY_TOP_SITES_BACKEND_H_