PaymentHandler: Implement PaymentInstruments.keys().

components/payments/mojom/payment_app.mojom

 // Copyright 2016 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.
 
 module payments.mojom;
 
 import "components/payments/mojom/payment_request.mojom";
 import "mojo/common/time.mojom";
 import "url/mojo/url.mojom";
 
@@ skipping 32 matching lines @@
 };
 
 interface PaymentManager {
   Init(string service_worker_scope);
   SetManifest(PaymentAppManifest payment_app_manifest)
       => (PaymentAppManifestError error);
   GetManifest()
       => (PaymentAppManifest payment_app_manifest, PaymentAppManifestError error);
   DeletePaymentInstrument(string instrument_key)
       => (PaymentHandlerStatus status);
+  GetPaymentInstrument(string instrument_key)
+      => (PaymentInstrument instrument, PaymentHandlerStatus status);
+  KeysOfPaymentInstruments()
+      => (array<string> keys, PaymentHandlerStatus status);
+  HasPaymentInstrument(string instrument_key)
+      => (PaymentHandlerStatus status);
   SetPaymentInstrument(string instrument_key, PaymentInstrument instrument)
       => (PaymentHandlerStatus status);
-  HasPaymentInstrument(string instrument_key)
-      => (PaymentHandlerStatus status);
-  GetPaymentInstrument(string instrument_key)
-      => (PaymentInstrument instrument, PaymentHandlerStatus status);
 };
 
 struct PaymentAppRequest {
   url.mojom.Url origin;
   array<PaymentMethodData> method_data;
   PaymentItem total;
   array<PaymentDetailsModifier> modifiers;
   string option_id;
 };
 
 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);
 };