Improve caption button behavior for video player.

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

Index: third_party/WebKit/Source/core/html/shadow/MediaControls.cpp
diff --git a/third_party/WebKit/Source/core/html/shadow/MediaControls.cpp b/third_party/WebKit/Source/core/html/shadow/MediaControls.cpp
index 9652b7e9ef2c5f24ffaaa634bc31ec9b6efccb3d..c41813d9332872faa8adf4b732700ec8320c6bc9 100644
--- a/third_party/WebKit/Source/core/html/shadow/MediaControls.cpp
+++ b/third_party/WebKit/Source/core/html/shadow/MediaControls.cpp
@@ -34,6 +34,7 @@
 #include "core/html/HTMLMediaElement.h"
 #include "core/html/shadow/MediaControlsWindowEventListener.h"
 #include "core/html/track/TextTrackContainer.h"
+#include "core/html/track/TextTrackList.h"
 #include "core/layout/LayoutObject.h"
 #include "core/layout/LayoutTheme.h"
 #include "platform/EventDispatchForbiddenScope.h"
@@ -556,6 +557,24 @@ void MediaControls::toggleTextTrackList() {
   m_textTrackList->setVisible(!m_textTrackList->isWanted());
 }
 
+void MediaControls::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 MediaControls::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());
+  }
+}
+
 void MediaControls::refreshCastButtonVisibility() {
   refreshCastButtonVisibilityWithoutUpdate();
   BatchedControlUpdate batch(this);