TrackEvent.track should be (VideoTrack or AudioTrack or TextTrack)?

Source/core/html/track/TrackEvent.h

 /*
  * Copyright (C) 2011 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 13 matching lines @@
  */
 
 #ifndef TrackEvent_h
 #define TrackEvent_h
 
 #include "core/events/Event.h"
 #include "core/html/track/TrackBase.h"
 
 namespace blink {
 
+class VideoTrackOrAudioTrackOrTextTrack;
+
 struct TrackEventInit : public EventInit {
     TrackEventInit();
 
     RefPtrWillBeMember<TrackBase> track;
 };
 
 class TrackEvent final : public Event {
     DEFINE_WRAPPERTYPEINFO();
 public:
     virtual ~TrackEvent();
 
     static PassRefPtrWillBeRawPtr<TrackEvent> create()
     {
         return adoptRefWillBeNoop(new TrackEvent);
     }
 
     static PassRefPtrWillBeRawPtr<TrackEvent> create(const AtomicString& type, const TrackEventInit& initializer)
     {
         return adoptRefWillBeNoop(new TrackEvent(type, initializer));
     }
 
     virtual const AtomicString& interfaceName() const override;
 
-    TrackBase* track() const { return m_track.get(); }
+    void track(VideoTrackOrAudioTrackOrTextTrack&);
 
     virtual void trace(Visitor*) override;
 
 private:
     TrackEvent();
     TrackEvent(const AtomicString& type, const TrackEventInit& initializer);
 
     RefPtrWillBeMember<TrackBase> m_track;
 };
 
 } // namespace blink
 
 #endif // TrackEvent_h