[Views] Allow dialog delegates to use a custom padding for the extra view

ui/views/window/dialog_delegate.cc

 // Copyright (c) 2012 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 "ui/views/window/dialog_delegate.h"
 
 #include "base/logging.h"
 #include "ui/accessibility/ax_view_state.h"
 #include "ui/base/l10n/l10n_util.h"
 #include "ui/strings/grit/ui_strings.h"
@@ skipping 59 matching lines @@
   // widgets to prevent top-level window behavior (independent movement, etc).
   params.child = parent && (delegate->GetModalType() == ui::MODAL_TYPE_CHILD);
   widget->Init(params);
   return widget;
 }
 
 View* DialogDelegate::CreateExtraView() {
   return NULL;
 }
 
+bool DialogDelegate::GetExtraViewPadding(int* padding) {
+  return false;
+}
+
 View* DialogDelegate::CreateTitlebarExtraView() {
   return NULL;
 }
 
 View* DialogDelegate::CreateFootnoteView() {
   return NULL;
 }
 
 bool DialogDelegate::Cancel() {
   return true;
@@ skipping 150 matching lines @@
   state->role = ui::AX_ROLE_DIALOG;
 }
 
 void DialogDelegateView::ViewHierarchyChanged(
     const ViewHierarchyChangedDetails& details) {
   if (details.is_add && details.child == this && GetWidget())
     NotifyAccessibilityEvent(ui::AX_EVENT_ALERT, true);
 }
 
 }  // namespace views