[Payments] Return the preferred payment method name to the merchant

components/payments/content/payment_request_spec.cc

Index: components/payments/content/payment_request_spec.cc
diff --git a/components/payments/content/payment_request_spec.cc b/components/payments/content/payment_request_spec.cc
index 5a92e86c71cc40d7986e3e1b941299e3bf3bb8fa..3435871ce3ef0be458e24359ecee492fea3facf6 100644
--- a/components/payments/content/payment_request_spec.cc
+++ b/components/payments/content/payment_request_spec.cc
@@ -10,10 +10,7 @@
 
 namespace payments {
 
-namespace {
-// Identifier for the basic card payment method in the PaymentMethodData.
-static const char* const kBasicCardMethodName = "basic-card";
-}  // namespace
+const char kBasicCardMethodName[] = "basic-card";
 
 PaymentRequestSpec::PaymentRequestSpec(
     mojom::PaymentOptionsPtr options,
@@ -39,6 +36,11 @@ void PaymentRequestSpec::RemoveObserver(Observer* observer) {
   observers_.RemoveObserver(observer);
 }
 
+bool PaymentRequestSpec::IsMethodSupportedThroughBasicCard(
+    const std::string& method_name) {
+  return basic_card_specified_networks_.count(method_name) > 0;
+}
+
 base::string16 PaymentRequestSpec::GetFormattedCurrencyAmount(
     const std::string& amount) {
   CurrencyFormatter* formatter = GetOrCreateCurrencyFormatter(
@@ -94,6 +96,8 @@ void PaymentRequestSpec::PopulateValidatedMethodData(
           supported_card_networks_.insert(supported_card_networks_.end(),
                                           card_networks.begin(),
                                           card_networks.end());
+          basic_card_specified_networks_.insert(card_networks.begin(),
+                                                card_networks.end());
           // Clear the set so that no further networks are added to
           // |supported_card_networks_|.
           card_networks.clear();
@@ -117,6 +121,8 @@ void PaymentRequestSpec::PopulateValidatedMethodData(
             auto card_it = card_networks.find(networks[supported_network]);
             if (card_it != card_networks.end()) {
               supported_card_networks_.push_back(networks[supported_network]);
+              basic_card_specified_networks_.insert(
+                  networks[supported_network]);
               card_networks.erase(card_it);
             }
           }