[Webview, Child Accounts] Automatically sign in to Chrome if needed.

components/supervised_user_error_page_strings.grdp

 <?xml version="1.0" encoding="utf-8"?>
 <grit-part>
       <!-- Supervised User Block Interstitial data -->
       <message name="IDS_BLOCK_INTERSTITIAL_TITLE" desc="A title for the supervised-user block interstitial page.">
         Site blocked
       </message>
       <message name="IDS_BLOCK_INTERSTITIAL_HEADER" desc="A heading for the supervised user when they attempt to visit a site that is not permitted by the manager.">
         You need permission from <ph name="NAME">$1<ex>John Doe</ex></ph> to visit this site
       </message>
       <message name="IDS_CHILD_BLOCK_INTERSTITIAL_HEADER" desc="A heading for the message to the child user when they attempt to visit a site that is not permitted by their parent.">
         Ask your parent
       </message>
       <message name="IDS_BLOCK_INTERSTITIAL_HEADER_ACCESS_REQUESTS_DISABLED" desc="A heading for the supervised user when they attempt to visit a site that is not permitted by the manager (and they can't ask for permission).">
         Looks like you don't have permission to visit this site
       </message>
+      <message name="IDS_BLOCK_INTERSTITIAL_HEADER_NOT_SIGNED_IN" desc="A heading for the supervised user when the status cannot be established because they haven't signed in to Chrome).">
+        Please start and sign in to Chrome before using this app.
+      </message>
       <message name="IDS_CHILD_BLOCK_INTERSTITIAL_MESSAGE" desc="A message for the child user when they attempt to visit a site that is not permitted by their parent.">
         Looks like you need permission to visit this site
       </message>
       <message name="IDS_BACK_BUTTON" desc="A button for going back to the last safe url after being blocked.">
         Go back
       </message>
       <message name="IDS_BLOCK_INTERSTITIAL_REQUEST_ACCESS_BUTTON" desc="A button for requesting access to blocked sites.">
         Ask permission
       </message>
       <message name="IDS_BLOCK_INTERSTITIAL_REQUEST_SENT_MESSAGE" desc="The text that tells the supervised user that a request has been sent.">
@@ skipping 40 matching lines @@
       </message>
       <message name="IDS_CHILD_BLOCK_MESSAGE_MANUAL_SINGLE_PARENT" desc="Message to be shown to a child when a site was blocked due to a manual blacklist entry and the child has one parent.">
         Your parent can unblock it for you
       </message>
       <message name="IDS_CHILD_BLOCK_MESSAGE_MANUAL_MULTI_PARENT" desc="Message to be shown to a child when a site was blocked due to a manual blacklist entry and the child has two parents.">
         Your parents can unblock it for you
       </message>
       <message name="IDS_SUPERVISED_USER_BLOCK_MESSAGE_MANUAL" desc="Message to be shown to a supervised user when a site is blocked due to a manual blacklist entry">
         Your manager can unblock it for you
       </message>
+      <message name="IDS_SUPERVISED_USER_NOT_SIGNED_IN" desc="Message to be shown to a supervised user who is not signed in to Chrome">
+        Please start and sign in to Chrome so that Chrome can check whether you are allowed to access this site.
+      </message>
 
 </grit-part>