Add "change" and "removetrack" events to TextTrackList.

Source/core/html/track/TextTrackList.h

Index: Source/core/html/track/TextTrackList.h
diff --git a/Source/core/html/track/TextTrackList.h b/Source/core/html/track/TextTrackList.h
index c2c619d50f757ec39dc2ea5f77424edbe8c9ba8b..3510970a36c4667d33db0621519a7a9faa511019 100644
--- a/Source/core/html/track/TextTrackList.h
+++ b/Source/core/html/track/TextTrackList.h
@@ -63,16 +63,21 @@ public:
     virtual ExecutionContext* executionContext() const OVERRIDE;
 
     DEFINE_ATTRIBUTE_EVENT_LISTENER(addtrack);
+    DEFINE_ATTRIBUTE_EVENT_LISTENER(change);
+    DEFINE_ATTRIBUTE_EVENT_LISTENER(removetrack);
 
     void clearOwner() { m_owner = 0; }
     Node* owner() const;
 
     bool isFiringEventListeners() { return m_dispatchingEvents; }
 
+    void scheduleChangeEvent();
+
 private:
     explicit TextTrackList(HTMLMediaElement*);
 
     void scheduleAddTrackEvent(PassRefPtr<TextTrack>);
+    void scheduleRemoveTrackEvent(PassRefPtr<TextTrack>);
     void asyncEventTimerFired(Timer<TextTrackList>*);
 
     void invalidateTrackIndexesAfterTrack(TextTrack*);