Add "Checking" spinner for server-side shipping address validation.

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 2429 matching lines @@
       </message>
       <message name="IDS_PAYMENTS_ADD_ADDRESS" desc="Text on a button that lets a user add a new shipping address.">
         Add address
       </message>
       <message name="IDS_PAYMENTS_ADD_PAYMENT_INSTRUMENT" desc="Text on a button that lets a user add a new payment method, like a credit card.">
         Add card
       </message>
       <message name="IDS_PAYMENTS_SELECT_SHIPPING_ADDRESS_FOR_SHIPPING_METHODS" desc="Text implying that a user needs to pick a shipping address to see the shipping methods.">
         Select a shipping address to check shipping methods.
       </message>
+      <message name="IDS_PAYMENTS_SHIPPING_ADDRESS_CHECKING" desc="Text explaining that the shipping address is being checked and verified.">
+        Checking
+      </message>
+      <message name="IDS_PAYMENTS_UNSUPPORTED_SHIPPING_ADDRESS" desc="Text implying that a user needs to pick a different shipping address, because the currently selected address is not supported.">
+        Unsupported shipping address. Select a different adddress.
+      </message>
 
       <!-- Migration strings -->
       <message name="IDS_TAB_SWITCHER_CALLOUT_HEADER" desc="Header for the Tab Switcher callout.">
         Quickly switch tabs
       </message>
       <message name="IDS_TAB_SWITCHER_CALLOUT_BODY" desc="Indicates that clicking the tab switcher button gives you quick access to your tabs.">
         Tap this button for quick access to your tabs.
       </message>
     </messages>
   </release>
 </grit>