Add an accessibility description for notification

ui/message_center/views/message_view.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/message_center/views/message_view.h"
 
 #include "base/strings/utf_string_conversions.h"
 #include "ui/accessibility/ax_node_data.h"
 #include "ui/base/l10n/l10n_util.h"
 #include "ui/base/models/simple_menu_model.h"
@@ skipping 95 matching lines @@
       gfx::ShadowDetails::Get(kShadowElevation, kShadowCornerRadius);
   gfx::Insets ninebox_insets = gfx::ShadowValue::GetBlurRegion(shadow.values) +
                                gfx::Insets(kShadowCornerRadius);
   SetBorder(views::CreateBorderPainter(
       std::unique_ptr<views::Painter>(views::Painter::CreateImagePainter(
           shadow.ninebox_image, ninebox_insets)),
       -gfx::ShadowValue::GetMargin(shadow.values)));
 }
 
 void MessageView::GetAccessibleNodeData(ui::AXNodeData* node_data) {
-  node_data->role = ui::AX_ROLE_BUTTON;
+  node_data->role = ui::AX_ROLE_NOTIFICATION;
   node_data->SetName(accessible_name_);
 }
 
 bool MessageView::OnMousePressed(const ui::MouseEvent& event) {
   if (!event.IsOnlyLeftMouseButton())
     return false;
 
   controller_->ClickOnNotification(notification_id_);
   return true;
 }
@@ skipping 104 matching lines @@
 }
 
 void MessageView::SetDrawBackgroundAsActive(bool active) {
   background_view_->background()->
       SetNativeControlColor(active ? kHoveredButtonBackgroundColor :
                                      kNotificationBackgroundColor);
   SchedulePaint();
 }
 
 }  // namespace message_center