Clean up forward declarations in Source/platform

Source/platform/mediastream/MediaStreamComponent.h

 /*
  * Copyright (C) 2011 Ericsson AB. All rights reserved.
  * Copyright (C) 2013 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.
@@ skipping 23 matching lines @@
 
 #include "platform/audio/AudioSourceProvider.h"
 #include "wtf/PassOwnPtr.h"
 #include "wtf/PassRefPtr.h"
 #include "wtf/RefCounted.h"
 #include "wtf/ThreadingPrimitives.h"
 #include "wtf/text/WTFString.h"
 
 namespace blink {
 
-class MediaStreamDescriptor;
 class MediaStreamSource;
 class WebAudioSourceProvider;
 
 class PLATFORM_EXPORT MediaStreamComponent : public RefCounted<MediaStreamComponent> {
 public:
     class ExtraData {
     public:
         virtual ~ExtraData() { }
     };
 
@@ skipping 50 matching lines @@
     bool m_enabled;
     bool m_muted;
     OwnPtr<ExtraData> m_extraData;
 };
 
 typedef Vector<RefPtr<MediaStreamComponent> > MediaStreamComponentVector;
 
 } // namespace blink
 
 #endif // MediaStreamComponent_h