[WebPayments] Factor out sheet-specific logic in Controllers.

chrome/browser/ui/views/payments/order_summary_view_controller.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 CHROME_BROWSER_UI_VIEWS_PAYMENTS_ORDER_SUMMARY_VIEW_CONTROLLER_H_
+#define CHROME_BROWSER_UI_VIEWS_PAYMENTS_ORDER_SUMMARY_VIEW_CONTROLLER_H_
+
+#include "base/macros.h"
+#include "chrome/browser/ui/views/payments/payment_request_sheet_controller.h"
+#include "ui/views/controls/button/button.h"
+
+namespace payments {
+
+class PaymentRequestImpl;
+class PaymentRequestDialog;
+
+// The PaymentRequestSheetController subtype for the Order Summary screen of the
+// Payment Request flow.
+class OrderSummaryViewController : public PaymentRequestSheetController,
+                                   public views::ButtonListener {
+ public:
+  OrderSummaryViewController(PaymentRequestImpl* impl,
+                             PaymentRequestDialog* dialog);
+  ~OrderSummaryViewController() override;
+
+  // PaymentRequestSheetController:
+  std::unique_ptr<views::View> CreateView() override;
+
+ private:
+  // views::ButtonListener:
+  void ButtonPressed(views::Button* sender, const ui::Event& event) override;
+
+  DISALLOW_COPY_AND_ASSIGN(OrderSummaryViewController);
+};
+
+}  // namespace payments
+
+#endif  // CHROME_BROWSER_UI_VIEWS_PAYMENTS_ORDER_SUMMARY_VIEW_CONTROLLER_H_