content: Cleanup class/struct forward declarations

content/browser/renderer_host/media/media_stream_manager.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.
 
 // MediaStreamManager is used to open/enumerate media capture devices (video
 // supported now). Call flow:
 // 1. GenerateStream is called when a render process wants to use a capture
 //    device.
 // 2. MediaStreamManager will ask MediaStreamUIController for permission to
 //    use devices and for which device to use.
@@ skipping 39 matching lines @@
 class AudioManager;
 }
 
 namespace url {
 class Origin;
 }
 
 namespace content {
 
 class AudioInputDeviceManager;
-class AudioOutputDeviceEnumerator;
-class BrowserContext;
 class FakeMediaStreamUIProxy;
-class MediaStreamDeviceSettings;
 class MediaStreamRequester;
 class MediaStreamUIProxy;
 class VideoCaptureManager;
 
 // MediaStreamManager is used to generate and close new media devices, not to
 // start the media flow. The classes requesting new media streams are answered
 // using MediaStreamRequester.
 class CONTENT_EXPORT MediaStreamManager
     : public MediaStreamProviderListener,
       public base::MessageLoop::DestructionObserver,
@@ skipping 384 matching lines @@
   std::vector<MediaStreamRequester*> device_change_subscribers_;
 
   GenerateStreamTestCallback generate_stream_test_callback_;
 
   DISALLOW_COPY_AND_ASSIGN(MediaStreamManager);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_MEDIA_MEDIA_STREAM_MANAGER_H_