Make a layer for popup MessageView

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 49 matching lines @@
 }  // namespace
 
 namespace message_center {
 
 MessageView::MessageView(MessageCenterController* controller,
                          const Notification& notification)
     : controller_(controller),
       notification_id_(notification.id()),
       notifier_id_(notification.notifier_id()),
       slide_out_controller_(this, this) {
+  SetPaintToLayer();

[Eliot Courtney, 2017/05/19 04:32:49]

Maybe add a comment as to why this has to be here?

+  layer()->SetFillsBoundsOpaquely(false);
   SetFocusBehavior(FocusBehavior::ALWAYS);
 
   // Create the opaque background that's above the view's shadow.
   background_view_ = new views::View();
   background_view_->set_background(
       views::Background::CreateSolidBackground(kNotificationBackgroundColor));
   AddChildView(background_view_);
 
   focus_painter_ = views::Painter::CreateSolidFocusPainter(
       kFocusBorderColor, gfx::Insets(0, 1, 3, 2));
@@ skipping 12 matching lines @@
 }
 
 // static
 gfx::Insets MessageView::GetShadowInsets() {
   return -gfx::ShadowValue::GetMargin(
       gfx::ShadowDetails::Get(kShadowElevation, kShadowCornerRadius).values);
 }
 
 void MessageView::SetIsNested() {
   is_nested_ = true;
-  SetPaintToLayer();
-  layer()->SetFillsBoundsOpaquely(false);
 
   const auto& shadow =
       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)));
 }
@@ skipping 113 matching lines @@
 }
 
 void MessageView::SetDrawBackgroundAsActive(bool active) {
   background_view_->background()->
       SetNativeControlColor(active ? kHoveredButtonBackgroundColor :
                                      kNotificationBackgroundColor);
   SchedulePaint();
 }
 
 }  // namespace message_center