Break two classes defined in json_value_serializer.cc, .h into separate files.

chrome/renderer/extensions/extension_helper.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/renderer/extensions/extension_helper.h"
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/command_line.h"
-#include "base/json/json_value_serializer.h"
+#include "base/json/json_string_value_serializer.h"
 #include "base/lazy_instance.h"
 #include "base/message_loop.h"
 #include "base/utf_string_conversions.h"
 #include "chrome/common/chrome_switches.h"
 #include "chrome/common/chrome_view_type.h"
 #include "chrome/common/extensions/extension_messages.h"
 #include "chrome/common/render_messages.h"
 #include "chrome/common/url_constants.h"
 #include "chrome/renderer/extensions/chrome_v8_context.h"
 #include "chrome/renderer/extensions/extension_dispatcher.h"
@@ skipping 329 matching lines @@
       routing_id(), *pending_app_info_));
   pending_app_info_.reset(NULL);
 }
 
 void ExtensionHelper::AddErrorToRootConsole(const string16& message) {
   if (render_view()->GetWebView() && render_view()->GetWebView()->mainFrame()) {
     render_view()->GetWebView()->mainFrame()->addMessageToConsole(
         WebConsoleMessage(WebConsoleMessage::LevelError, message));
   }
 }