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

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

 // Copyright 2017 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_request_sheet_controller.h"
 
 #include "chrome/browser/ui/views/payments/payment_request_dialog_view.h"
 #include "chrome/browser/ui/views/payments/payment_request_views_util.h"
 #include "components/strings/grit/components_strings.h"
 #include "ui/base/l10n/l10n_util.h"
@@ skipping 10 matching lines @@
   : request_(request), dialog_(dialog) {
   DCHECK(request_);
   DCHECK(dialog_);
 }
 
 std::unique_ptr<views::Button>
 PaymentRequestSheetController::CreatePrimaryButton() {
   return nullptr;
 }
 
+std::unique_ptr<views::View> PaymentRequestSheetController::CreateExtraView() {
+  return nullptr;
+}
+
 void PaymentRequestSheetController::ButtonPressed(
     views::Button* sender, const ui::Event& event) {
   switch (static_cast<PaymentRequestCommonTags>(sender->tag())) {
     case PaymentRequestCommonTags::CLOSE_BUTTON_TAG:
       dialog()->CloseDialog();
       break;
     case PaymentRequestCommonTags::BACK_BUTTON_TAG:
       dialog()->GoBack();
       break;
     case PaymentRequestCommonTags::PAYMENT_REQUEST_COMMON_TAG_MAX:
@@ skipping 44 matching lines @@
   container->SetLayoutManager(layout);
 
   views::ColumnSet* columns = layout->AddColumnSet(0);
   columns->AddColumn(views::GridLayout::LEADING, views::GridLayout::CENTER,
                      0, views::GridLayout::USE_PREF, 0, 0);
   columns->AddPaddingColumn(1, 0);
   columns->AddColumn(views::GridLayout::TRAILING, views::GridLayout::CENTER,
                      0, views::GridLayout::USE_PREF, 0, 0);
 
   layout->StartRow(0, 0);
-  std::unique_ptr<views::View> leading_buttons_container =
-      base::MakeUnique<views::View>();
-
-  // TODO(anthonyvd): Add the other buttons that can eventually go into this
-  // footer.
-
-  layout->AddView(leading_buttons_container.release());
+  std::unique_ptr<views::View> extra_view = CreateExtraView();
+  if (extra_view)
+    layout->AddView(extra_view.release());
+  else
+    layout->SkipColumns(1);
 
   std::unique_ptr<views::View> trailing_buttons_container =
       base::MakeUnique<views::View>();
 
-  constexpr int kButtonSpacing = 10;
   trailing_buttons_container->SetLayoutManager(new views::BoxLayout(
       views::BoxLayout::kHorizontal,
       kPaymentRequestRowHorizontalInsets,
       kPaymentRequestRowVerticalInsets,
-      kButtonSpacing));
+      kPaymentRequestButtonSpacing));
 
   std::unique_ptr<views::Button> primary_button = CreatePrimaryButton();
   if (primary_button)
     trailing_buttons_container->AddChildView(primary_button.release());
 
   views::LabelButton* button = views::MdTextButton::CreateSecondaryUiButton(
       this, l10n_util::GetStringUTF16(IDS_CANCEL));
   button->set_tag(static_cast<int>(PaymentRequestCommonTags::CLOSE_BUTTON_TAG));
   trailing_buttons_container->AddChildView(button);
 
   layout->AddView(trailing_buttons_container.release());
 
   return container;
 }
 
 }  // namespace payments