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

Source/core/html/track/TrackEvent.cpp

 /*
  * 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
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  *
  * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
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  */
 
 #include "config.h"
+#include "core/html/track/TrackEvent.h"
 
-#include "core/html/track/TrackEvent.h"
+#include "bindings/core/v8/UnionTypesCore.h"
+#include "core/html/track/AudioTrack.h"
+#include "core/html/track/TextTrack.h"
+#include "core/html/track/VideoTrack.h"
 
 namespace blink {
 
 TrackEventInit::TrackEventInit()
 {
 }
 
 
 TrackEvent::TrackEvent()
 {
 }
 
 TrackEvent::TrackEvent(const AtomicString& type, const TrackEventInit& initializer)
     : Event(type, initializer)
     , m_track(initializer.track)
 {
 }
 
 TrackEvent::~TrackEvent()
 {
 }
 
 const AtomicString& TrackEvent::interfaceName() const
 {
     return EventNames::TrackEvent;
 }
 
+void TrackEvent::track(VideoTrackOrAudioTrackOrTextTrack& returnValue)
+{
+    if (!m_track)
+        return;
+
+    switch (m_track->type()) {
+    case TrackBase::TextTrack:
+        returnValue.setTextTrack(toTextTrack(m_track.get()));
+        break;
+    case TrackBase::AudioTrack:
+        returnValue.setAudioTrack(toAudioTrack(m_track.get()));
+        break;
+    case TrackBase::VideoTrack:
+        returnValue.setVideoTrack(toVideoTrack(m_track.get()));
+        break;
+    default:
+        ASSERT_NOT_REACHED();
+    }
+}
+
 void TrackEvent::trace(Visitor* visitor)
 {
     visitor->trace(m_track);
     Event::trace(visitor);
 }
 
 } // namespace blink