[Payments] Add a Pay button in the Order summary screen

chrome/browser/ui/views/payments/payment_sheet_view_controller.cc

 // 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.
 
 #include "chrome/browser/ui/views/payments/payment_sheet_view_controller.h"
 
 #include <algorithm>
 #include <memory>
 #include <utility>
 #include <vector>
@@ skipping 153 matching lines @@
 
 PaymentSheetViewController::PaymentSheetViewController(
     PaymentRequest* request,
     PaymentRequestDialogView* dialog)
     : PaymentRequestSheetController(request, dialog),
       pay_button_(nullptr),
       widest_name_column_view_width_(ComputeWidestNameColumnViewWidth()) {
   request->AddObserver(this);
 }
 
-PaymentSheetViewController::~PaymentSheetViewController() {}
+PaymentSheetViewController::~PaymentSheetViewController() {
+  request()->RemoveObserver(this);
+}
 
 std::unique_ptr<views::View> PaymentSheetViewController::CreateView() {
   std::unique_ptr<views::View> content_view = base::MakeUnique<views::View>();
 
   views::GridLayout* layout = new views::GridLayout(content_view.get());
   content_view->SetLayoutManager(layout);
   views::ColumnSet* columns = layout->AddColumnSet(0);
   columns->AddColumn(views::GridLayout::FILL, views::GridLayout::CENTER,
                      1, views::GridLayout::USE_PREF, 0, 0);
 
@@ skipping 201 matching lines @@
       CreateContactInfoSectionContent(), std::unique_ptr<views::View>(nullptr),
       widest_name_column_view_width_);
   section->set_tag(static_cast<int>(
       PaymentSheetViewControllerTags::SHOW_CONTACT_INFO_BUTTON));
   section->set_id(
       static_cast<int>(DialogViewID::PAYMENT_SHEET_CONTACT_INFO_SECTION));
   return section;
 }
 
 }  // namespace payments