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

third_party/WebKit/Source/modules/payments/PaymentAppResponse.idl

Index: third_party/WebKit/Source/modules/payments/PaymentAppResponse.idl
diff --git a/third_party/WebKit/Source/modules/payments/PaymentAppResponse.idl b/third_party/WebKit/Source/modules/payments/PaymentAppResponse.idl
new file mode 100644
index 0000000000000000000000000000000000000000..3712e52a458c987865252bae696300f994045b6d
--- /dev/null
+++ b/third_party/WebKit/Source/modules/payments/PaymentAppResponse.idl
@@ -0,0 +1,10 @@
+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// https://w3c.github.io/webpayments-payment-apps-api/#idl-def-paymentappresponse
+
+dictionary PaymentAppResponse {
+    DOMString methodName;
+    object details;
+};