PaymentHandler: Implement PaymentInstruments.has().

content/browser/payments/payment_manager.h

 // 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.
 
 #ifndef CONTENT_BROWSER_PAYMENTS_PAYMENT_MANAGER_H_
 #define CONTENT_BROWSER_PAYMENTS_PAYMENT_MANAGER_H_
 
 #include <string>
 
 #include "base/macros.h"
@@ skipping 25 matching lines @@
   void SetManifest(payments::mojom::PaymentAppManifestPtr manifest,
                    const SetManifestCallback& callback) override;
   void GetManifest(const GetManifestCallback& callback) override;
   void DeletePaymentInstrument(
       const std::string& instrument_key,
       const DeletePaymentInstrumentCallback& callback) override;
   void SetPaymentInstrument(
       const std::string& instrument_key,
       payments::mojom::PaymentInstrumentPtr details,
       const SetPaymentInstrumentCallback& callback) override;
+  void HasPaymentInstrument(
+      const std::string& instrument_key,
+      const HasPaymentInstrumentCallback& callback) override;
   void GetPaymentInstrument(
       const std::string& instrument_key,
       const GetPaymentInstrumentCallback& callback) override;
 
   // Called when an error is detected on binding_.
   void OnConnectionError();
 
   // PaymentAppContextImpl owns PaymentManager
   PaymentAppContextImpl* payment_app_context_;
 
   GURL scope_;
   mojo::Binding<payments::mojom::PaymentManager> binding_;
   base::WeakPtrFactory<PaymentManager> weak_ptr_factory_;
   DISALLOW_COPY_AND_ASSIGN(PaymentManager);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_PAYMENTS_PAYMENT_MANAGER_H_