Include HTMLMediaElement.h only where needed

Source/modules/mediasource/MediaSourceBase.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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 17 matching lines @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #ifndef MediaSourceBase_h
 #define MediaSourceBase_h
 
 #include "core/dom/ActiveDOMObject.h"
 #include "core/events/EventTarget.h"
 #include "core/html/HTMLMediaSource.h"
 #include "core/html/URLRegistry.h"
+#include "public/platform/WebMediaSource.h"
 #include "wtf/PassOwnPtr.h"
 #include "wtf/RefCounted.h"
 #include "wtf/Vector.h"
 
 namespace blink {
-class WebMediaSource;
 class WebSourceBuffer;
 }
 
 namespace WebCore {
 
 class ExceptionState;
 class GenericEventQueue;
 
 class MediaSourceBase : public RefCountedWillBeRefCountedGarbageCollected<MediaSourceBase>, public HTMLMediaSource, public ActiveDOMObject, public EventTargetWithInlineData {
     DEFINE_EVENT_TARGET_REFCOUNTING(RefCountedWillBeRefCountedGarbageCollected<MediaSourceBase>);
@@ skipping 53 matching lines @@
     OwnPtr<blink::WebMediaSource> m_webMediaSource;
     AtomicString m_readyState;
     OwnPtr<GenericEventQueue> m_asyncEventQueue;
     // FIXME: oilpan: This should become a Member. For now, m_attachedElement will be cleared by the HTMLMediaElement destructor.
     HTMLMediaElement* m_attachedElement;
 };
 
 }
 
 #endif