Clean up HTMLTrackElement.kind invalid/missing value default handling

third_party/WebKit/Source/core/html/track/TextTrack.h

 /*
  * Copyright (C) 2011 Google Inc. All rights reserved.
  * Copyright (C) 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
@@ skipping 106 matching lines @@
     const AtomicString& interfaceName() const override;
     ExecutionContext* getExecutionContext() const override;
 
     DECLARE_VIRTUAL_TRACE();
 
     DECLARE_VIRTUAL_TRACE_WRAPPERS();
 
 protected:
     TextTrack(const AtomicString& kind, const AtomicString& label, const AtomicString& language, const AtomicString& id, TextTrackType);
 
-    bool isValidKind(const AtomicString& kind) const override { return isValidKindKeyword(kind); }
-    AtomicString invalidValueDefaultKind() const override { return metadataKeyword(); }
-
     void addListOfCues(HeapVector<Member<TextTrackCue>>&);
 
 private:
     CueTimeline* cueTimeline() const;
 
     TextTrackCueList* ensureTextTrackCueList();
     Member<TextTrackCueList> m_cues;
     Member<TextTrackCueList> m_activeCues;
 
     VTTRegionList* ensureVTTRegionList();
     Member<VTTRegionList> m_regions;
 
     Member<TextTrackList> m_trackList;
     AtomicString m_mode;
     TextTrackType m_trackType;
     ReadinessState m_readinessState;
     int m_trackIndex;
     int m_renderedTrackIndex;
     bool m_hasBeenConfigured;
 };
 
 DEFINE_TRACK_TYPE_CASTS(TextTrack, WebMediaPlayer::TextTrack);
 
 } // namespace blink
 
 #endif // TextTrack_h