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

chrome/browser/ui/views/payments/payment_request_sheet_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_PAYMENT_REQUEST_SHEET_CONTROLLER_H_
 #define CHROME_BROWSER_UI_VIEWS_PAYMENTS_PAYMENT_REQUEST_SHEET_CONTROLLER_H_
 
 #include <memory>
 
 #include "base/macros.h"
@@ skipping 31 matching lines @@
   // Caller should not take ownership of the result.
   PaymentRequestDialogView* dialog() { return dialog_; }
 
  protected:
   // Creates and returns the primary action button for this sheet. It's
   // typically a blue button with the "Pay" or "Done" labels. Subclasses may
   // return an empty std::unique_ptr (nullptr) to indicate that no primary
   // button should be displayed. The caller takes ownership of the button but
   // the view is guaranteed to be outlived by the controller so subclasses may
   // retain a raw pointer to the returned button (for example to control its
-  // enabled state).
+  // enabled state). See comment on CreatePaymentView for an illustration of the
+  // layout.
   virtual std::unique_ptr<views::Button> CreatePrimaryButton();
 
+  // Creates and returns the view to be displayed next to the "Pay" and "Cancel"
+  // buttons. May return an empty std::unique_ptr (nullptr) to indicate that no
+  // extra view is to be displayed.The caller takes ownership of the view but
+  // the view is guaranteed to be outlived by the controller so subclasses may
+  // retain a raw pointer to the returned view (for example to control its
+  // enabled state). See comment on CreatePaymentView for an illustration of the
+  // layout.
+  virtual std::unique_ptr<views::View> CreateExtraView();
+
   // views::VectorIconButtonDelegate:
   void ButtonPressed(views::Button* sender, const ui::Event& event) override;
 
   // Creates a view to be displayed in the PaymentRequestDialog.
   // |header_view| is the view displayed on top of the dialog, containing title,
   // (optional) back button, and close buttons.
   // |content_view| is displayed between |header_view| and the pay/cancel
   // buttons. Also adds the footer, returned by CreateFooterView(), which is
   // clamped to the bottom of the containing view.  The returned view takes
   // ownership of |header_view|, |content_view|, and the footer.
   // +---------------------------+
   // |        HEADER VIEW        |
   // +---------------------------+
   // |          CONTENT          |
   // |           VIEW            |
   // +---------------------------+
-  // |            | CANCEL | PAY | <-- footer
+  // | EXTRA VIEW | PAY | CANCEL | <-- footer
   // +---------------------------+
   std::unique_ptr<views::View> CreatePaymentView(
       std::unique_ptr<views::View> header_view,
       std::unique_ptr<views::View> content_view);
 
   // Creates the row of button containing the Pay, cancel, and extra buttons.
   // |controller| is installed as the listener for button events.
   std::unique_ptr<views::View> CreateFooterView();
 
  private:
   // Not owned. Will outlive this.
   PaymentRequest* request_;
   // Not owned. Will outlive this.
   PaymentRequestDialogView* dialog_;
 
   DISALLOW_COPY_AND_ASSIGN(PaymentRequestSheetController);
 };
 
 }  // namespace payments
 
 #endif  // CHROME_BROWSER_UI_VIEWS_PAYMENTS_PAYMENT_REQUEST_SHEET_CONTROLLER_H_