Support text track selection in video controls

content/app/strings/content_strings.grd

 <?xml version="1.0" encoding="UTF-8"?>
 
 <!-- This file contains definitions of resources that will be translated for
 each locale. Specifically, these are UI strings that are used by content that
 need to be translated for each locale.-->
 
 <!-- Some of these strings and string descriptions were taken from
 WebKit/win/WebCoreLocalizedStrings.cpp so we include the original license
 below:
 
@@ skipping 588 matching lines @@
         exit full screen
       </message>
 
       <message name="IDS_AX_MEDIA_SHOW_CLOSED_CAPTIONS_BUTTON" desc="accessibility role description for show closed captions button">
         show closed captions
       </message>
 
       <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>
 
       <message name="IDS_AX_MEDIA_AUDIO_ELEMENT_HELP" desc="Accessible help of audio controls">
         audio
       </message>
 
       <message name="IDS_AX_MEDIA_VIDEO_ELEMENT_HELP" desc="Accessible help of video">
         video
@@ skipping 51 matching lines @@
         start displaying closed captions
       </message>
 
       <message name="IDS_AX_MEDIA_HIDE_CLOSED_CAPTIONS_BUTTON_HELP" desc="accessibility help description for hide closed captions button">
         stop displaying closed captions
       </message>
 
       <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>
 
       <message name="IDS_AX_MILLISECOND_FIELD_TEXT" desc="Accessible description of the millisecond field in a date/time control">
         Milliseconds
       </message>
 
       <message name="IDS_AX_MINUTE_FIELD_TEXT" desc="Accessible description of the minute field in a date/time control">
         Minutes
@@ skipping 144 matching lines @@
       <message name="IDS_FORM_VALIDATION_STEP_MISMATCH_CLOSE_TO_LIMIT" desc="Heading or short sentence shown when a form control value in a webpage should be aligned to a step value specified by the page author, but a user speficified non-aligned value. e.g. A number type field, minimum value is 0, and step value is 4. If A user-specified value is not a multiple of 4, this warning message is shown.">
         Please enter a valid value. The nearest valid value is <ph name="VALID_VALUE">$1<ex>0</ex></ph>.
       </message>
       <message name="IDS_FORM_VALIDATION_TOO_LONG" desc="Heading or short sentence shown when a form control in a webpage needs to be shorter than a length specified by the page author, but a user specified long value.">
         Please shorten this text to <ph name="MAX_CHARACTERS">$2<ex>100</ex></ph> characters or less (you are currently using <ph name="CURRENT_LENGTH">$1<ex>101</ex></ph> characters).
       </message>
       <message name="IDS_FORM_VALIDATION_TOO_SHORT" desc="Heading or short sentence shown when a form control in a webpage needs to be longer than a length specified by the page author, but a user specified short value.">
         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">

[philipj_slow, 2016/03/01 08:51:40]

It looks like you have accidentally reverted part of
https://codereview.chromium.org/1007443004 here, presumably when resolving a
conflict.

[srivats, 2016/03/30 00:46:42]

Sorry. Fixed it

+        Couldn't load plug-in.
       </message>
 
     </messages>
   </release>
 </grit>