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

chrome/browser/history/top_sites_cache.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_CACHE_H_
 #define CHROME_BROWSER_HISTORY_TOP_SITES_CACHE_H_
 #pragma once
 
-#include <algorithm>
 #include <map>
-#include <string>
+#include <utility>
 
 #include "base/memory/ref_counted.h"
 #include "chrome/browser/history/history_types.h"
 
-class RefCountedBytes;
-
 namespace history {
 
 // TopSitesCache caches the top sites and thumbnails for TopSites.
 class TopSitesCache {
  public:
   TopSitesCache();
   ~TopSitesCache();
 
   // The top sites.
   void SetTopSites(const MostVisitedURLList& top_sites);
@@ skipping 68 matching lines @@
   // Generated from the redirects to and from the most visited pages. See
   // description above typedef for details.
   CanonicalURLs canonical_urls_;
 
   DISALLOW_COPY_AND_ASSIGN(TopSitesCache);
 };
 
 }  // namespace history
 
 #endif  // CHROME_BROWSER_HISTORY_TOP_SITES_CACHE_H_