Allow the cast tray to function as expected when the installed extension is missing API methods.

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 260 matching lines @@
       </message>
       <message name="IDS_ASH_STATUS_TRAY_CAST_NO_DEVICE" desc="The label used in the tray popup to notify that no cast devices are available.">
         No cast devices
       </message>
       <message name="IDS_ASH_STATUS_TRAY_CAST_OPTIONS" desc="The label used in the tray popup to manage cast options.">
         Options
       </message>
       <message name="IDS_ASH_STATUS_TRAY_CAST_STOP" desc="The label used in the tray popup to stop casting.">
         Stop
       </message>
+      <message name="IDS_ASH_STATUS_TRAY_CAST_UNKNOWN_CAST_TYPE" desc="The label used when we have detected we are casting but do not know if we are casting a tab or the desktop.">
+        Casting
+      </message>
+      <message name="IDS_ASH_STATUS_TRAY_CAST_UNKNOWN_RECEIVER" desc="The label used when we have detected we are casting but do not know the name of the receiver.">
+        Unknown receiver
+      </message>
 
       <message name="IDS_ASH_STATUS_TRAY_BLUETOOTH" desc="The label used as the header in the bluetooth popup.">
         Bluetooth
       </message>
       <message name="IDS_ASH_STATUS_TRAY_BLUETOOTH_ENABLED" desc="The label used in the tray popup to notify that bluetooth is enabled.">
         Bluetooth enabled
       </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>
@@ skipping 155 matching lines @@
 
       <!-- ChromeOS-specific strings -->
       <if expr="chromeos">
         <part file="ash_chromeos_strings.grdp" />
       </if>
 
     </messages>
   </release>
 </grit>