[Autofill] Fix bug in settings when card has no billing address.

Bug: 789059
Change-Id: I60aee9281d367fe8df545fef59ad920462d10a87
Reviewed-on: https://chromium-review.googlesource.com/794095Reviewed-by: Steven Bennetts <stevenjb@chromium.org>
Commit-Queue: Sebastien Seguin-Gagnon <sebsg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#519808}

chrome/browser/extensions/api/autofill_private/autofill_private_api.cc

@@ -399,7 +399,7 @@ ExtensionFunction::ResponseAction AutofillPrivateSaveCreditCardFunction::Run() {
         base::UTF8ToUTF16(*card->expiration_year));
   }
 
-  if (!card->billing_address_id->empty()) {
+  if (card->billing_address_id) {
     credit_card.set_billing_address_id(*card->billing_address_id);
   }