Clean up forward declarations in Source/modules

Source/modules/mediastream/MediaStreamRegistry.h

 /*
  * Copyright (C) 2011 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 16 matching lines @@
 
 #include "core/html/URLRegistry.h"
 #include "platform/heap/Handle.h"
 #include "wtf/HashMap.h"
 #include "wtf/PassRefPtr.h"
 #include "wtf/text/StringHash.h"
 
 namespace blink {
 
 class KURL;
-class MediaStream;
 class MediaStreamDescriptor;
 
 class MediaStreamRegistry final : public URLRegistry {
 public:
     // Returns a single instance of MediaStreamRegistry.
     static MediaStreamRegistry& registry();
 
     // Registers a blob URL referring to the specified stream data.
     virtual void registerURL(SecurityOrigin*, const KURL&, URLRegistrable*) override;
     virtual void unregisterURL(const KURL&) override;
     virtual bool contains(const String&) override;
 
     MediaStreamDescriptor* lookupMediaStreamDescriptor(const String& url);
 
 private:
     MediaStreamRegistry();
     PersistentHeapHashMap<String, Member<MediaStreamDescriptor> > m_streamDescriptors;
 };
 
 } // namespace blink
 
 #endif // MediaStreamRegistry_h