Update SetPaintToLayer to accept LayerType

ash/common/system/web_notification/web_notification_tray.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 "ash/common/system/web_notification/web_notification_tray.h"
 
 #include "ash/common/material_design/material_design_controller.h"
 #include "ash/common/session/session_state_delegate.h"
 #include "ash/common/shelf/shelf_constants.h"
 #include "ash/common/shelf/wm_shelf.h"
@@ skipping 106 matching lines @@
   std::unique_ptr<TrayBubbleWrapper> bubble_wrapper_;
 
   DISALLOW_COPY_AND_ASSIGN(WebNotificationBubbleWrapper);
 };
 
 class WebNotificationItem : public views::View, public gfx::AnimationDelegate {
  public:
   WebNotificationItem(gfx::AnimationContainer* container,
                       WebNotificationTray* tray)
       : tray_(tray) {
-    SetPaintToLayer(true);
+    SetPaintToLayer();
     layer()->SetFillsBoundsOpaquely(false);
     views::View::SetVisible(false);
     set_owned_by_client();
 
     SetLayoutManager(new views::FillLayout);
 
     animation_.reset(new gfx::SlideAnimation(this));
     animation_->SetContainer(container);
     animation_->SetSlideDuration(kTrayItemAnimationDurationMS);
     animation_->SetTweenType(gfx::Tween::LINEAR);
@@ skipping 529 matching lines @@
 
 message_center::MessageCenterBubble*
 WebNotificationTray::GetMessageCenterBubbleForTest() {
   if (!message_center_bubble())
     return nullptr;
   return static_cast<message_center::MessageCenterBubble*>(
       message_center_bubble()->bubble());
 }
 
 }  // namespace ash