[Web Payments] Fix some ScrollView issues 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 101 matching lines @@
 
   // All these are not owned. Will outlive this.
   PaymentRequestSpec* spec_;
   PaymentRequestState* state_;
   PaymentRequestDialogView* dialog_;
 
   // This view is owned by its encompassing ScrollView.
   views::View* pane_;
   views::View* content_view_;
 
+  // Hold on to the ScrollView because it must be explicitly laid out in some
+  // cases.
+  std::unique_ptr<views::ScrollView> scroll_;
+
   DISALLOW_COPY_AND_ASSIGN(PaymentRequestSheetController);
 };
 
 }  // namespace payments
 
 #endif  // CHROME_BROWSER_UI_VIEWS_PAYMENTS_PAYMENT_REQUEST_SHEET_CONTROLLER_H_