Implement automatic text track selection for 'metadata' tracks

Source/core/html/HTMLMediaElement.cpp

 /*
  * Copyright (C) 2007, 2008, 2009, 2010, 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
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 2906 matching lines @@
             RefPtrWillBeRawPtr<TextTrack> textTrack = currentlyEnabledTracks[i];
             if (textTrack != trackToEnable)
                 textTrack->setMode(TextTrack::disabledKeyword());
         }
     }
 
     if (trackToEnable)
         trackToEnable->setMode(TextTrack::showingKeyword());
 }
 
+void HTMLMediaElement::configureMetadataTextTrackGroup(const TrackGroup& group)
+{
+    ASSERT(group.tracks.size());
+
+    // https://html.spec.whatwg.org/multipage/embedded-content.html#honor-user-preferences-for-automatic-text-track-selection
+
+    // 4. If there are any text tracks in the media element's list of text
+    // tracks whose text track kind is metadata that correspond to track
+    // elements with a default attribute set whose text track mode is set to
+    // disabled, then set the text track mode of all such tracks to hidden
+    for (auto& textTrack : group.tracks) {
+        if (textTrack->mode() != TextTrack::disabledKeyword())
+            continue;
+        if (!textTrack->isDefault())
+            continue;
+        textTrack->setMode(TextTrack::hiddenKeyword());
+    }
+}
+
 void HTMLMediaElement::configureTextTracks()
 {
     TrackGroup captionAndSubtitleTracks(TrackGroup::CaptionsAndSubtitles);
     TrackGroup descriptionTracks(TrackGroup::Description);
     TrackGroup chapterTracks(TrackGroup::Chapter);
     TrackGroup metadataTracks(TrackGroup::Metadata);
     TrackGroup otherTracks(TrackGroup::Other);
 
     if (!m_textTracks)
         return;
@@ skipping 35 matching lines @@
         currentGroup->tracks.append(textTrack);
     }
 
     if (captionAndSubtitleTracks.tracks.size())
         configureTextTrackGroup(captionAndSubtitleTracks);
     if (descriptionTracks.tracks.size())
         configureTextTrackGroup(descriptionTracks);
     if (chapterTracks.tracks.size())
         configureTextTrackGroup(chapterTracks);
     if (metadataTracks.tracks.size())
-        configureTextTrackGroup(metadataTracks);
+        configureMetadataTextTrackGroup(metadataTracks);
     if (otherTracks.tracks.size())
         configureTextTrackGroup(otherTracks);

[philipj_slow, 2015/01/29 10:34:52]

This looks like it's not per spec if you want to remove it in another CL.
There's also some renaming to be done that would make all of this more
spec-like.

[fs, 2015/01/29 12:05:51]

Yes, I noticed this as well, and I wondered what tracks would be "other"...
replacing it with a ASSERT_NOT_REACHED above ought to do it...

 
     textTracksChanged();
 }
 
 bool HTMLMediaElement::havePotentialSourceChild()
 {
     // Stash the current <source> node and next nodes so we can restore them after checking
     // to see there is another potential.
     RefPtrWillBeRawPtr<HTMLSourceElement> currentSourceNode = m_currentSourceNode;
     RefPtrWillBeRawPtr<Node> nextNode = m_nextChildNodeToConsider;
@@ skipping 1102 matching lines @@
 
 #if ENABLE(WEB_AUDIO)
 void HTMLMediaElement::clearWeakMembers(Visitor* visitor)
 {
     if (!visitor->isAlive(m_audioSourceNode) && audioSourceProvider())
         audioSourceProvider()->setClient(nullptr);
 }
 #endif
 
 }