Remove HTMLMediaElement::textTrackKindChanged

Source/core/html/track/TextTrack.cpp

 /*
  * 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
@@ skipping 138 matching lines @@
 
     m_trackList = trackList;
     invalidateTrackIndex();
 }
 
 void TextTrack::setKind(const AtomicString& newKind)
 {
     AtomicString oldKind = kind();
     TrackBase::setKind(newKind);
 
-    if (mediaElement() && oldKind != kind())
-        mediaElement()->textTrackKindChanged(this);
+    // If kind changes from visual to non-visual and mode is 'showing', then force mode to 'hidden'.

[philipj_slow, 2015/02/23 13:41:46]

Does this correspond to anything in the HTML spec? It seems reasonable, but
there's nothing equivalent when setting mode. I think this means that the follow
two bits of code won't result in the same state, if we start with kind
'captions' and mode 'hidden':

track.kind = 'metadata';
track.mode = 'showing';
// mode is showing

track.mode = 'showing';
track.kind = 'metadata';
// mode is hidden

That seems a bit odd.

[fs, 2015/02/23 14:00:02]

AFAIK, no. The spec says "The kind of track can change dynamically, in the case
of a text track corresponding to a track element." but doesn't prescribe any
specific handling for that case.
Odd indeed. I suspect what should really happen here (in TextTrack::setKind) is
that any currently rendered cues gets hidden.

+    if (oldKind != kind() && mode() == showingKeyword()) {
+        if (kind() != captionsKeyword() && kind() != subtitlesKeyword())
+            setMode(hiddenKeyword());
+    }
 }
 
 void TextTrack::setMode(const AtomicString& mode)
 {
     ASSERT(mode == disabledKeyword() || mode == hiddenKeyword() || mode == showingKeyword());
 
     // On setting, if the new value isn't equal to what the attribute would currently
     // return, the new value must be processed as follows ...
     if (m_mode == mode)
         return;
@@ skipping 278 matching lines @@
 DEFINE_TRACE(TextTrack)
 {
     visitor->trace(m_cues);
     visitor->trace(m_regions);
     visitor->trace(m_trackList);
     TrackBase::trace(visitor);
     EventTargetWithInlineData::trace(visitor);
 }
 
 } // namespace blink