chrome: Cleanup class/struct forward declarations

chrome/test/media_router/media_router_base_browsertest.h

 // Copyright 2015 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_TEST_MEDIA_ROUTER_MEDIA_ROUTER_BASE_BROWSERTEST_H_
 #define CHROME_TEST_MEDIA_ROUTER_MEDIA_ROUTER_BASE_BROWSERTEST_H_
 
 #include <string>
 
 #include "base/callback.h"
 #include "base/macros.h"
 #include "base/synchronization/waitable_event.h"
 #include "base/timer/timer.h"
 #include "chrome/browser/extensions/extension_apitest.h"
 #include "extensions/browser/process_manager_observer.h"
 
 namespace media_router {
 
-class MediaRouter;
-
 /**
  * Base class for media router browser test.
  *
  * It provides the basic functions for integration and e2e browser tests,
  * including install unpacked or packed extension at beginning of the test,
  * uninstall the extension at the end of the test.
  *
  * This class accepts two flags to specify the location of MR extension:
  * 1. "--extension-crx" flag to specify the packed extension location
  * 2. "--extension-unpacked" flag to specify the unpacked extension location
@@ skipping 46 matching lines @@
   std::string extension_id_;
   bool extension_host_created_;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(MediaRouterBaseBrowserTest);
 };
 
 }  // namespace media_router
 
 #endif  // CHROME_TEST_MEDIA_ROUTER_MEDIA_ROUTER_BASE_BROWSERTEST_H_