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

ash/system/user/user_card_view.cc

 // Copyright 2014 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/system/user/user_card_view.h"
 
 #include <algorithm>
 #include <memory>
 #include <vector>
 
@@ skipping 275 matching lines @@
 
 UserCardView::UserCardView(LoginStatus login_status, int user_index)
     : user_index_(user_index) {
   auto* layout = new views::BoxLayout(views::BoxLayout::kHorizontal, 0, 0,
                                       kTrayPopupLabelHorizontalPadding);
   SetLayoutManager(layout);
   layout->set_minimum_cross_axis_size(kTrayPopupItemMinHeight);
   layout->set_cross_axis_alignment(
       views::BoxLayout::CROSS_AXIS_ALIGNMENT_CENTER);
 
-  set_background(views::Background::CreateSolidBackground(kBackgroundColor));
+  set_background(views::Background::CreateThemedSolidBackground(
+      this, ui::NativeTheme::kColorId_BubbleBackground));
 
   Shell::Get()->media_controller()->AddObserver(this);
 
   if (login_status == LoginStatus::PUBLIC)
     AddPublicModeUserContent();
   else
     AddUserContent(layout, login_status);
 }
 
 UserCardView::~UserCardView() {
@@ skipping 134 matching lines @@
   media_capture_container_ = new views::View();
   media_capture_container_->SetLayoutManager(new views::FillLayout());
   media_capture_container_->AddChildView(media_capture_icon_);
   AddChildView(media_capture_container_);
 
   Shell::Get()->media_controller()->RequestCaptureState();
 }
 
 }  // namespace tray
 }  // namespace ash