Clean up forward declarations in Source/modules

Source/modules/mediastream/MediaDevicesRequest.h

 /*
  * Copyright (C) 2014 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 18 matching lines @@
 #include "core/dom/ActiveDOMObject.h"
 #include "modules/mediastream/MediaDeviceInfo.h"
 #include "modules/mediastream/MediaDeviceInfoCallback.h"
 #include "platform/heap/Handle.h"
 #include "wtf/PassOwnPtr.h"
 
 namespace blink {
 
 class Document;
 class ExceptionState;
-class MediaStreamDescriptor;
 class UserMediaController;
 
 class MediaDevicesRequest final : public GarbageCollectedFinalized<MediaDevicesRequest>, public ActiveDOMObject {
 public:
     static MediaDevicesRequest* create(ExecutionContext*, UserMediaController*, MediaDeviceInfoCallback*, ExceptionState&);
     virtual ~MediaDevicesRequest();
 
     MediaDeviceInfoCallback* callback() const { return m_callback.get(); }
     Document* ownerDocument();
 
@@ skipping 10 matching lines @@
     MediaDevicesRequest(ExecutionContext*, UserMediaController*, MediaDeviceInfoCallback*);
 
     UserMediaController* m_controller;
 
     Member<MediaDeviceInfoCallback> m_callback;
 };
 
 } // namespace blink
 
 #endif // MediaDevicesRequest_h