Support text track selection in video controls

Source/core/html/shadow/MediaControlElementTypes.h

Index: Source/core/html/shadow/MediaControlElementTypes.h
diff --git a/Source/core/html/shadow/MediaControlElementTypes.h b/Source/core/html/shadow/MediaControlElementTypes.h
index cb306cf59e96799bbda5e22cd6d04650df02bbbc..c80f9000bd7385a39e92b6eb24912c99376599fa 100644
--- a/Source/core/html/shadow/MediaControlElementTypes.h
+++ b/Source/core/html/shadow/MediaControlElementTypes.h
@@ -48,11 +48,14 @@ enum MediaControlElementType {
     MediaSliderThumb,
     MediaShowClosedCaptionsButton,
     MediaHideClosedCaptionsButton,
+    MediaClosedCaptionsTrackListContainer,
+    MediaClosedCaptionsTrackList,
     MediaUnMuteButton,
     MediaPauseButton,
     MediaTimelineContainer,
     MediaCurrentTimeDisplay,
     MediaTimeRemainingDisplay,
+    MediaTrackSelectionCheckmark,
     MediaControlsPanel,
     MediaVolumeSliderContainer,
     MediaVolumeSlider,
@@ -78,6 +81,7 @@ class MediaControlElement : public WillBeGarbageCollectedMixin {
 public:
     void hide();
     void show();
+    bool isVisible();
 
     MediaControlElementType displayType() { return m_displayType; }