Improve caption button behavior for video player.

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

Index: third_party/WebKit/Source/core/html/shadow/MediaControlElements.cpp
diff --git a/third_party/WebKit/Source/core/html/shadow/MediaControlElements.cpp b/third_party/WebKit/Source/core/html/shadow/MediaControlElements.cpp
index 022370bfdd79ba204e54fd57a969e6312dfd4761..19c55590ee818d9064eb5529cd074d1676df96a1 100644
--- a/third_party/WebKit/Source/core/html/shadow/MediaControlElements.cpp
+++ b/third_party/WebKit/Source/core/html/shadow/MediaControlElements.cpp
@@ -471,6 +471,16 @@ void MediaControlTextTrackListElement::defaultEventHandler(Event* 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();
@@ -499,15 +509,21 @@ void MediaControlTextTrackListElement::disableShowingTextTracks() {
 }
 
 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;
 }