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

chrome/android/java/strings/android_chrome_strings.grd

Index: chrome/android/java/strings/android_chrome_strings.grd
diff --git a/chrome/android/java/strings/android_chrome_strings.grd b/chrome/android/java/strings/android_chrome_strings.grd
index 7796f00d6f7bf1c0fe35bcddba8d30744399277f..486080832169440b93639b4c7b31c7e370ad629f 100644
--- a/chrome/android/java/strings/android_chrome_strings.grd
+++ b/chrome/android/java/strings/android_chrome_strings.grd
@@ -1888,6 +1888,9 @@ To obtain new licenses, connect to the internet and play your downloaded content
       <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.">