Improve caption button behavior for video player.

third_party/WebKit/Source/core/html/shadow/MediaControlElements.cpp

 /*
  * Copyright (C) 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2012 Google 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.
@@ skipping 453 matching lines @@
       showTextTrackAtIndex(trackIndex);
       mediaElement().disableAutomaticTextTrackSelection();
     }
 
     event->setDefaultHandled();
   }
   MediaControlDivElement::defaultEventHandler(event);
 }
 
 void MediaControlTextTrackListElement::setVisible(bool visible) {
+  if (mediaElement().textTracks()->length() == 1) {
+    if (mediaElement().textTracks()->hasShowingTracks()) {
+      TextTrack* track = mediaElement().textTracks()->anonymousIndexedGetter(0);
+      track->setMode(TextTrack::hiddenKeyword());
+    } else {
+      showTextTrackAtIndex(0);
+    }
+    return;
+  }

[mlamouri (slow - plz ping), 2016/10/28 13:02:37]

Maybe this logic could be moved to the ClosedCaption button instead? Maybe
`disableShowingTextTracks()` and `showTextTrackAtIndex()` could move to a common
place like MediaControls to avoid re-implementing part of the logic in the
closed captions button?

[Finnur, 2016/10/28 14:12:22]

Yeah, I like that idea. Done.

+
   if (visible) {
     setIsWanted(true);
     refreshTextTrackListMenu();
   } else {
     setIsWanted(false);
   }
 }
 
 void MediaControlTextTrackListElement::showTextTrackAtIndex(
     unsigned indexToEnable) {
   TextTrackList* trackList = mediaElement().textTracks();
   if (indexToEnable >= trackList->length())
     return;
   TextTrack* track = trackList->anonymousIndexedGetter(indexToEnable);
   if (track && track->canBeRendered())
     track->setMode(TextTrack::showingKeyword());
 }
 
 void MediaControlTextTrackListElement::disableShowingTextTracks() {
   TextTrackList* trackList = mediaElement().textTracks();
   for (unsigned i = 0; i < trackList->length(); ++i) {
     TextTrack* track = trackList->anonymousIndexedGetter(i);
     if (track->mode() == TextTrack::showingKeyword())
       track->setMode(TextTrack::disabledKeyword());
   }
 }
 
 String MediaControlTextTrackListElement::getTextTrackLabel(TextTrack* track) {
-  if (!track)
+  if (!track) {
     return mediaElement().locale().queryString(
         WebLocalizedString::TextTracksOff);
+  }
 
   String trackLabel = track->label();
 
   if (trackLabel.isEmpty())
+    trackLabel = track->language();
+
+  if (trackLabel.isEmpty()) {
     trackLabel = String(mediaElement().locale().queryString(
-        WebLocalizedString::TextTracksNoLabel));
+        WebLocalizedString::TextTracksNoLabel,
+        String::number(track->trackIndex() + 1)));
+  }
 
   return trackLabel;
 }
 
 // TextTrack parameter when passed in as a nullptr, creates the "Off" list item
 // in the track list.
 Element* MediaControlTextTrackListElement::createTextTrackListItem(
     TextTrack* track) {
   int trackIndex = track ? track->trackIndex() : trackIndexOffValue;
   HTMLLabelElement* trackItem = HTMLLabelElement::create(document());
@@ skipping 504 matching lines @@
 MediaControlCurrentTimeDisplayElement*
 MediaControlCurrentTimeDisplayElement::create(MediaControls& mediaControls) {
   MediaControlCurrentTimeDisplayElement* element =
       new MediaControlCurrentTimeDisplayElement(mediaControls);
   element->setShadowPseudoId(
       AtomicString("-webkit-media-controls-current-time-display"));
   return element;
 }
 
 }  // namespace blink