Implement new volume mute button.

ash/ash_strings.grd

 <?xml version="1.0" encoding="UTF-8"?>
 
 <!--
 This file contains the strings for ash.
 -->
 
 <grit base_dir="." latest_public_release="0" current_release="1"
       source_lang_id="en" enc_check="möl">
   <outputs>
     <output filename="grit/ash_strings.h" type="rc_header">
@@ skipping 279 matching lines @@
       </message>
       <message name="IDS_ASH_STATUS_TRAY_BLUETOOTH_DISABLED" desc="The label used in the tray popup to notify that bluetooth is disabled.">
         Bluetooth disabled
       </message>
       <message name="IDS_ASH_STATUS_TRAY_BRIGHTNESS" desc="The accessible text for the brightness slider.">
         Brightness
       </message>
       <message name="IDS_ASH_STATUS_TRAY_VOLUME" desc="The accessible text for the volume slider.">
         Volume
       </message>
+      <message name="IDS_ASH_STATUS_TRAY_VOLUME_MUTE" desc="The label text for the volume mute segment.">
+        mute
+      </message>
       <message name="IDS_ASH_STATUS_TRAY_DISABLE_BLUETOOTH" desc="The label used in the tray popup to disable bluetooth.">
         Disable Bluetooth
       </message>
       <message name="IDS_ASH_STATUS_TRAY_ENABLE_BLUETOOTH" desc="The label used in the tray popup to enable bluetooth.">
         Enable Bluetooth
       </message>
       <message name="IDS_ASH_STATUS_TRAY_BLUETOOTH_SETTINGS" desc="The label used in the tray popup for bluetooth settings.">
         Bluetooth settings...
       </message>
       <message name="IDS_ASH_STATUS_TRAY_BLUETOOTH_ADD_DEVICE" desc="The label used in the tray popup to add a bluetooth device.">
@@ skipping 96 matching lines @@
       <message name="IDS_ASH_WEB_NOTFICATION_TRAY_SETTINGS" desc="The menu entry or button for visiting the appropriate settings page.">
         Settings...
       </message>
       <message name="IDS_ASH_WEB_NOTFICATION_TRAY_CLOSE_ALL" desc="The button for closing all notifications.">
         Close All
       </message>
     </messages>
   </release>
 </grit>