extensions: Cleanup class/struct fwd declarations

extensions/browser/extension_message_filter.h

 // Copyright 2014 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 EXTENSIONS_BROWSER_EXTENSION_MESSAGE_FILTER_H_
 #define EXTENSIONS_BROWSER_EXTENSION_MESSAGE_FILTER_H_
 
 #include <string>
 #include <vector>
 
 #include "base/compiler_specific.h"
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
 #include "components/keyed_service/core/keyed_service_shutdown_notifier.h"
 #include "content/public/browser/browser_message_filter.h"
 
 class GURL;
 
 namespace content {
 class BrowserContext;
 }
 
-namespace gfx {
-class Size;
-}
-
 namespace extensions {
 class EventRouter;
 
 // This class filters out incoming extension-specific IPC messages from the
 // renderer process. It is created and destroyed on the UI thread and handles
 // messages there.
 class ExtensionMessageFilter : public content::BrowserMessageFilter {
  public:
   ExtensionMessageFilter(int render_process_id,
                          content::BrowserContext* context);
@@ skipping 54 matching lines @@
 
   // Only access from the UI thread.
   content::BrowserContext* browser_context_;
 
   DISALLOW_COPY_AND_ASSIGN(ExtensionMessageFilter);
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_BROWSER_EXTENSION_MESSAGE_FILTER_H_