Implement IsReadyToPay handling

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 b212a68e0ee4a904b4293bbc7ea1ef5cc1133e9b..bb8dd2f890d08756025ced6b9b84a329cd6a0ce8 100644
--- a/chrome/android/java/strings/android_chrome_strings.grd
+++ b/chrome/android/java/strings/android_chrome_strings.grd
@@ -2588,6 +2588,9 @@ You can control the Physical Web in Chrome Settings.
       <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>
+      <message name="IDS_PAYMENTS_ANDROID_APP_ERROR" desc="Error message that is shown when an Android payment application fails to start.">
+        Unable to launch payment app
+      </message>
 
       <!-- Migration strings -->
       <message name="IDS_TAB_SWITCHER_CALLOUT_HEADER" desc="Header for the Tab Switcher callout.">