Clean up forward declarations in Source/core/html

Source/core/html/HTMLMediaElement.h

 /*
  * Copyright (C) 2007, 2008, 2009, 2010, 2011, 2012, 2013 Apple 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 21 matching lines @@
 #include "core/html/track/TextTrack.h"
 #include "core/html/track/TextTrackCue.h"
 #include "core/html/track/vtt/VTTCue.h"
 #include "platform/PODIntervalTree.h"
 #include "platform/Supplementable.h"
 #include "platform/graphics/media/MediaPlayer.h"
 #include "public/platform/WebMediaPlayerClient.h"
 #include "public/platform/WebMimeRegistry.h"
 
 namespace blink {
-class WebContentDecryptionModule;
 class WebInbandTextTrack;
 class WebLayer;
 }
 
 namespace blink {
 
 #if ENABLE(WEB_AUDIO)
 class AudioSourceProvider;
 class AudioSourceProviderClient;
 #endif
@@ skipping 578 matching lines @@
 inline bool isHTMLMediaElement(const HTMLElement& element)
 {
     return isHTMLAudioElement(element) || isHTMLVideoElement(element);
 }
 
 DEFINE_HTMLELEMENT_TYPE_CASTS_WITH_FUNCTION(HTMLMediaElement);
 
 } // namespace blink
 
 #endif // HTMLMediaElement_h