Introduce a type of View background that stays in sync with its host

ui/message_center/views/message_bubble_base.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_bubble_base.h"
 
 #include "base/bind.h"
 #include "base/location.h"
 #include "base/single_thread_task_runner.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "ui/message_center/message_center_style.h"
 #include "ui/views/widget/widget.h"
 #include "ui/views/widget/widget_observer.h"
 
 namespace {
 // Delay laying out the MessageBubbleBase until all notifications have been
 // added and icons have had a chance to load.
 const int kUpdateDelayMs = 50;
 const int kMessageBubbleBaseDefaultMaxHeight = 400;
 }
 
 namespace message_center {
 
-const SkColor MessageBubbleBase::kBackgroundColor =
-    SkColorSetRGB(0xfe, 0xfe, 0xfe);
-
 MessageBubbleBase::MessageBubbleBase(MessageCenter* message_center,
                                      MessageCenterTray* tray)
     : message_center_(message_center),
       tray_(tray),
       bubble_view_(NULL),
       max_height_(kMessageBubbleBaseDefaultMaxHeight),
       weak_ptr_factory_(this) {
 }
 
 MessageBubbleBase::~MessageBubbleBase() {
@@ skipping 34 matching lines @@
     views::TrayBubbleView::AnchorAlignment anchor_alignment) {
   views::TrayBubbleView::InitParams init_params(
       anchor_alignment,
       kNotificationWidth,
       kNotificationWidth);
   init_params.bg_color = kBackgroundDarkColor;
   return init_params;
 }
 
 }  // namespace message_center