PaymentApp: Implement respondWith() in PaymentRequestEvent. (content side)

components/payments/content/payment_app.mojom

Index: components/payments/content/payment_app.mojom
diff --git a/components/payments/content/payment_app.mojom b/components/payments/content/payment_app.mojom
index 0d9f7c655ad95ce00108c6592d6e4bf1858121e4..d86c037da0b1028f0cf433335f5e9c4dfead94e9 100644
--- a/components/payments/content/payment_app.mojom
+++ b/components/payments/content/payment_app.mojom
@@ -5,6 +5,7 @@
 module payments.mojom;
 
 import "components/payments/content/payment_request.mojom";
+import "mojo/common/time.mojom";
 import "url/mojo/url.mojom";
 
 enum PaymentAppManifestError {
@@ -42,3 +43,15 @@ struct PaymentAppRequest {
   array<PaymentDetailsModifier> modifiers;
   string optionId;
 };
+
+struct PaymentAppResponse {
+  string method_name;
+  string stringified_details;
+};
+
+// This interface is provided to pass a payment app response from payment
+// request event in renderer side to browser side by calling respondWith().
+interface PaymentAppResponseCallback {
+  OnPaymentAppResponse(PaymentAppResponse response,
+                       mojo.common.mojom.Time dispatch_event_time);
+};