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 e56c6856c15fb6f07d73bd5dbcbcf5c803cca8ec..ba2663af712e84162391d174eb143193c9e2e406 100644
--- a/content/app/strings/content_strings.grd
+++ b/content/app/strings/content_strings.grd
@@ -445,11 +445,11 @@ 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>
@@ -521,7 +521,7 @@ 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>
@@ -686,8 +686,16 @@ 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_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>