Cleanup: Remove forward declarations in various chrome/browser directories.

chrome/browser/history/top_sites_database.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_DATABASE_H_
 #define CHROME_BROWSER_HISTORY_TOP_SITES_DATABASE_H_
 #pragma once
 
 #include <map>
 #include <string>
 
 #include "base/gtest_prod_util.h"
 #include "base/memory/ref_counted.h"
 #include "chrome/browser/history/history_types.h"
 #include "chrome/browser/history/url_database.h"  // For DBCloseScoper.
 #include "sql/meta_table.h"
 
 class FilePath;
-class RefCountedMemory;
-class SkBitmap;
 
 namespace sql {
 class Connection;
 }
 
 namespace history {
 
 class TopSitesDatabase {
  public:
   TopSitesDatabase();
@@ skipping 77 matching lines @@
 
   // See description above class.
   bool may_need_history_migration_;
 
   DISALLOW_COPY_AND_ASSIGN(TopSitesDatabase);
 };
 
 }  // namespace history
 
 #endif  // CHROME_BROWSER_HISTORY_TOP_SITES_DATABASE_H_