bookmarks: Forward declare some classes in header files when possible.

chrome/browser/bookmarks/bookmark_storage.cc

 // Copyright (c) 2012 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.
 
 #include "chrome/browser/bookmarks/bookmark_storage.h"
 
 #include "base/bind.h"
 #include "base/compiler_specific.h"
 #include "base/file_path.h"
 #include "base/file_util.h"
 #include "base/json/json_file_value_serializer.h"
 #include "base/json/json_string_value_serializer.h"
 #include "base/metrics/histogram.h"
 #include "base/time.h"
 #include "chrome/browser/bookmarks/bookmark_codec.h"
+#include "chrome/browser/bookmarks/bookmark_index.h"
 #include "chrome/browser/bookmarks/bookmark_model.h"
 #include "chrome/common/chrome_constants.h"
 #include "chrome/common/startup_metric_utils.h"
 #include "content/public/browser/browser_context.h"
 #include "content/public/browser/browser_thread.h"
 
 using base::TimeTicks;
 using content::BrowserThread;
 
 namespace {
@@ skipping 146 matching lines @@
     NOTREACHED();
     return false;
   }
 
   std::string data;
   if (!SerializeData(&data))
     return false;
   writer_.WriteNow(data);
   return true;
 }