Add device policy to disallow shutdown - WebUI modifications

chrome/app/chromeos_strings.grdp

 <?xml version="1.0" encoding="utf-8"?>
 <!-- ChromeOS-specific strings (included from generated_resources.grd).
      Everything in this file is wrapped in <if expr="chromeos">. -->
 <grit-part>
   <message name="IDS_EMPTY_STRING" desc="Empty string, exist only to make code generic. No translation required.">
   </message>
   <message name="IDS_CHROMEBOOK" desc="The localized name for Chromebook.">
     Chromebook
   </message>
   <message name="IDS_CHROMEBOX" desc="The localized name for Chromebox">
@@ skipping 1742 matching lines @@
   </message>
   <message name="IDS_DIAGNOSE_BUTTON" desc="The label for the button that launches the connectivity diagnostics app from the network error page">
     Diagnose
   </message>
   <message name="IDS_MANAGE_CERTIFICATES" desc="The label for the button that launches the certificate manager from the network error page">
     Manage certificates
   </message>
   <message name="IDS_OFFLINE_LOGIN_HTML" desc="Text which suggests enter as an existing user when valid network isn't presented.">
     If you've already registered on this device, you can <ph name="LINK2_START">$1<ex>&gt;a&lt;</ex></ph>sign in as an existing user<ph name="LINK2_END">$2<ex>&gt;/a&lt;</ex></ph>.
   </message>
+  <message name="IDS_RESTART_BUTTON" desc="Text shown on reboot button on login/locker screen">
+    Restart
+  </message>
   <message name="IDS_SHUTDOWN_BUTTON" desc="Text shown on shutdown button on login/locker screen">
     Shut down
   </message>
   <message name="IDS_KIOSK_APPS_BUTTON" desc="Text shown on a button that brings up the kiosk apps menu on login screen">
     Apps
   </message>
   <message name="IDS_LOGIN_USER_ADDING_BANNER" desc="Text shown on a banner in user adding screen.">
     Add an account to multiple sign-in. All signed-in accounts can be accessed without a password, so this feature should only be used with trusted accounts.
   </message>
   <message name="IDS_LOGIN_OOBE_HELP_DIALOG_TITLE" desc="Default title for help dialogs during OOBE/login">
@@ skipping 4246 matching lines @@
   <message name="IDS_SET_TIME_BUTTON_CLOSE" desc="Text for the button to close the window.">
     Done
   </message>
   <message name="IDS_SET_TIME_DATE_LABEL" desc="Label for the date input element.">
     System date
   </message>
   <message name="IDS_SET_TIME_TIME_LABEL" desc="Label for the time input element.">
     System time
   </message>
 </grit-part>