content: Cleanup class/struct forward declarations

content/public/browser/web_ui_message_handler.h

 // 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.
 
 #ifndef CONTENT_PUBLIC_BROWSER_WEB_UI_MESSAGE_HANDLER_H_
 #define CONTENT_PUBLIC_BROWSER_WEB_UI_MESSAGE_HANDLER_H_
 
 #include <vector>
 
 #include "base/gtest_prod_util.h"
 #include "base/logging.h"
 #include "base/strings/string16.h"
 #include "content/common/content_export.h"
 #include "content/public/browser/web_ui.h"
 
-class GURL;
 class WebUIBrowserTest;
 
 namespace base {
-class DictionaryValue;
 class ListValue;
 class Value;
 }
 
 namespace content {
 
 class WebUI;
 class WebUIImpl;
 
 // Messages sent from the DOM are forwarded via the WebUI to handler
@@ skipping 95 matching lines @@
 
   // True if the page is for JavaScript calls from this handler.
   bool javascript_allowed_;
 
   WebUI* web_ui_;
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_BROWSER_WEB_UI_MESSAGE_HANDLER_H_