Clean forward declaration in public

public/platform/WebMediaStream.h

 /*
  * 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.
  * 2.  Redistributions in binary form must reproduce the above copyright
  *     notice, this list of conditions and the following disclaimer in the
@@ skipping 15 matching lines @@
 #define WebMediaStream_h
 
 #include "WebCommon.h"
 #include "WebNonCopyable.h"
 #include "WebPrivatePtr.h"
 #include "WebVector.h"
 
 namespace blink {
 
 class MediaStreamDescriptor;
-class WebMediaStreamSource;
 class WebMediaStreamTrack;
 class WebString;
 
 class WebMediaStream {
 public:
     class ExtraData {
     public:
         virtual ~ExtraData() { }
     };
 
@@ skipping 38 matching lines @@
     BLINK_PLATFORM_EXPORT WebMediaStream& operator=(const WTF::PassRefPtr<MediaStreamDescriptor>&);
 #endif
 
 private:
     WebPrivatePtr<MediaStreamDescriptor> m_private;
 };
 
 } // namespace blink
 
 #endif // WebMediaStream_h