Added Aura notification that relaunch and powerwash is required in case of downgrade.

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 268 matching lines @@
         Manage devices...
       </message>
       <message name="IDS_ASH_STATUS_TRAY_BLUETOOTH_DISCOVERING" desc="The label used in the tray popup to show bluetooth is discovering devices.">
         Scanning for devices...
       </message>
 
       <message name="IDS_ASH_STATUS_TRAY_UPDATE" desc="The label used in the tray popup to notify that the user should restart to get system updates.">
         Restart to update
       </message>
 
+      <message name="IDS_ASH_STATUS_TRAY_RESTART_AND_POWERWASH_TO_UPDATE" desc="The label used in the tray popup to notify that the user should restart and powerwash the device to get system updates.">
+        Restart and powerwash to update
+      </message>
+
       <message name="IDS_ASH_STATUS_TRAY_VOLUME" desc="The accessible text for the volume slider.">
         Volume
       </message>
 
       <message name="IDS_ASH_STATUS_TRAY_UNKNOWN_DISPLAY_NAME" desc="Label shown in tray for a display whose name is unknown.">
         Unknown Display
       </message>
       <message name="IDS_ASH_STATUS_TRAY_DRIVE_SYNCING" desc="The label in the tray to indicate onoing file sync operations.">
         Syncing <ph name="count">$1<ex>3</ex></ph> file(s)
       </message>
@@ skipping 119 matching lines @@
 
       <!-- ChromeOS-specific strings -->
       <if expr="chromeos">
         <part file="ash_chromeos_strings.grdp" />
       </if>
 
     </messages>
   </release>
 </grit>