[Payments] Desktop: Error message in the 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 38 matching lines @@
 
   // 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).
   virtual std::unique_ptr<views::Button> CreatePrimaryButton();
 
+  // Returns the text that should be on the secondary button, by default
+  // "Cancel".
+  virtual base::string16 GetSecondaryButtonLabel();
+
   // Returns whether this sheet should display a back arrow in the header next
   // to the title.
   virtual bool ShouldShowHeaderBackArrow();
 
   // Returns the title to be displayed in this sheet's header.
   virtual base::string16 GetSheetTitle() = 0;
 
   // Implemented by subclasses to populate |content_view| with the views that
   // should be displayed in their content area (between the header and the
   // footer). This may be called at view creation time as well as anytime
@@ skipping 44 matching lines @@
 
   // This view is owned by its encompassing ScrollView.
   views::View* content_view_;
 
   DISALLOW_COPY_AND_ASSIGN(PaymentRequestSheetController);
 };
 
 }  // namespace payments
 
 #endif  // CHROME_BROWSER_UI_VIEWS_PAYMENTS_PAYMENT_REQUEST_SHEET_CONTROLLER_H_