Support text track selection in video controls

content/app/strings/content_strings.grd

Index: content/app/strings/content_strings.grd
diff --git a/content/app/strings/content_strings.grd b/content/app/strings/content_strings.grd
index e853a97fedb991796ae93a09d3ac15ef39ce7f57..e3d2fa8f8bda348e086b9c71f145fbfe9cc2207d 100644
--- a/content/app/strings/content_strings.grd
+++ b/content/app/strings/content_strings.grd
@@ -508,11 +508,11 @@ below:
       <message name="IDS_AX_MEDIA_HIDE_CLOSED_CAPTIONS_BUTTON" desc="accessibility role description for hide closed captions button">
         hide closed captions
       </message>
-      
+
       <message name="IDS_AX_MEDIA_CAST_OFF_BUTTON" desc="accessibility role description for remote playback button">
         play on remote device
       </message>
-      
+
       <message name="IDS_AX_MEDIA_CAST_ON_BUTTON" desc="accessibility role description for remote playback control button">
         control remote playback
       </message>
@@ -584,7 +584,7 @@ below:
       <message name="IDS_AX_MEDIA_CAST_OFF_BUTTON_HELP" desc="accessibility help description for remote playback button">
         play on remote device
       </message>
-      
+
       <message name="IDS_AX_MEDIA_CAST_ON_BUTTON_HELP" desc="accessibility help description for remote playback control button">
         control remote playback
       </message>
@@ -749,8 +749,24 @@ below:
         Please lengthen this text to <ph name="MIN_CHARACTERS">$2<ex>101</ex></ph> characters or more (you are currently using <ph name="CURRENT_LENGTH">$1<ex>100</ex></ph> characters).
       </message>
 
-      <message name="IDS_PLUGIN_INITIALIZATION_ERROR" desc="A message displayed when a plugin failed to load">
-        Couldn't load plugin.
+      <message name="IDS_MEDIA_TRACKS_NO_LABEL" desc="Menu item label for a text track that has no name specified">
+        Unknown
+      </message>
+
+      <message name="IDS_MEDIA_TRACKS_SUBTITLES" desc="Menu section heading for a list of tracks">
+        Subtitles
+      </message>
+
+      <message name="IDS_MEDIA_TRACKS_CAPTIONS_MARKER" desc="Short marker for caption tracks">
+        ''' [CC]
+      </message>
+
+      <message name="IDS_MEDIA_TRACKS_OFF" desc="Menu item label for a text track that represents disabling closed captions">
+        Off
+      </message>
+
+      <message name="IDS_PLUGIN_INITIALIZATION_ERROR" desc="A message displayed when a plug-in failed to load">
+        Couldn't load plug-in.
       </message>
 
     </messages>