Add a ProgressDialog during sign-in flow when GMS is updated.

chrome/android/java/strings/android_chrome_strings.grd

 <?xml version="1.0" encoding="UTF-8"?>
 
 <!-- android_chrome_strings.grd contains strings for Chrome for Android.
 
 FAQ:
   - How do I add, change, or remove a string?
       Just update this file.
   - Translations will happen automatically??
       Yes, indeed. Just add your string before the branch point and
       make the description good.
@@ skipping 1870 matching lines @@
       </message>
       <message name="IDS_SIGNIN_HI_NAME" desc="Title welcoming the user by their name after they have signed in.">
         Hi, <ph name="FULL_NAME">%1$s<ex>John Smith</ex></ph>
       </message>
       <message name="IDS_SIGNIN_SIGNED_IN_DESCRIPTION_UCA_ADDENDUM" desc="Additional explanation for child accounts that synced settings are managed by parents.">
         Your parents help manage these settings.
       </message>
       <message name="IDS_SIGNIN_SIGNED_IN_SETTINGS_DESCRIPTION" desc="Label of the section containing the link to go to the settings page.">
         Control how this works in <ph name="BEGIN_LINK1">&lt;LINK1&gt;</ph>Settings<ph name="END_LINK1">&lt;/LINK1&gt;</ph>
       </message>
+      <message name="IDS_SIGNIN_GMS_UPDATING" desc="Message notifying user that Google Play Services is still updating.">
+        Waiting for Google Play Services to finish updating.
+      </message>
 
       <!-- External Navigation Strings -->
       <message name="IDS_EXTERNAL_APP_LEAVE_INCOGNITO_WARNING" desc="Alert dialog text warning that user that incognito mode does not continue into external apps.">
         Leaving incognito mode if this link is opened in an external application. Continue?
       </message>
       <message name="IDS_EXTERNAL_APP_LEAVE_INCOGNITO_WARNING_TITLE" desc="Title for incognito external intent. [CHAR-LIMIT=24]">
         Warning
       </message>
       <message name="IDS_EXTERNAL_APP_RESTRICTED_ACCESS_ERROR" desc="A message shown to the user if Chrome receives a file view request to something Chrome does not have access to view.">
         Chrome does not have access to the requested resource.
@@ skipping 972 matching lines @@
       </message>
       <message name="IDS_KEYBOARD_SHORTCUT_CHROME_FEATURE_GROUP_HEADER" desc="A text label that appears above a list of shortcuts that are related to the Chrome app features. This group is part of several groups of keyboard shortcuts all shown in a dialog.">
         Google Chrome feature shortcuts
       </message>
       <message name="IDS_KEYBOARD_SHORTCUT_WEBPAGE_GROUP_HEADER" desc="A text label that appears above a list of shortcuts that are related to manipulation of the current tab window. This group is part of several groups of keyboard shortcuts all shown in a dialog.">
         Webpage shortcuts
       </message>
     </messages>
   </release>
 </grit>