[Web Payments] Add a mechanism to build item lists in the PR dialog.

chrome/browser/ui/views/payments/payment_method_view_controller.h

 // 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.
 
 #ifndef CHROME_BROWSER_UI_VIEWS_PAYMENTS_PAYMENT_METHOD_VIEW_CONTROLLER_H_
 #define CHROME_BROWSER_UI_VIEWS_PAYMENTS_PAYMENT_METHOD_VIEW_CONTROLLER_H_
 
 #include "base/macros.h"
+#include "chrome/browser/ui/views/payments/payment_request_item_list.h"
 #include "chrome/browser/ui/views/payments/payment_request_sheet_controller.h"
 
 namespace payments {
 
 class PaymentRequest;
 class PaymentRequestDialogView;
 
 // The PaymentRequestSheetController subtype for the Payment Method screen of
 // the Payment Request flow.
 class PaymentMethodViewController : public PaymentRequestSheetController {
  public:
   // Does not take ownership of the arguments, which should outlive this object.
   PaymentMethodViewController(PaymentRequest* request,
                               PaymentRequestDialogView* dialog);
   ~PaymentMethodViewController() override;
 
   // PaymentRequestSheetController:
   std::unique_ptr<views::View> CreateView() override;
 
  private:
   // PaymentRequestSheetController:
+  std::unique_ptr<views::View> CreateExtraView() override;
   void ButtonPressed(views::Button* sender, const ui::Event& event) override;
 
+  PaymentRequestItemList payment_method_list_;
+
   DISALLOW_COPY_AND_ASSIGN(PaymentMethodViewController);
 };
 
 }  // namespace payments
 
 #endif  // CHROME_BROWSER_UI_VIEWS_PAYMENTS_PAYMENT_METHOD_VIEW_CONTROLLER_H_