Reland: mash: Convert TrayBackgroundView to wm common types

ash/system/tray/system_tray_unittest.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/system/tray/system_tray.h"
 
 #include <vector>
 
 #include "ash/common/accessibility_delegate.h"
+#include "ash/common/system/tray/system_tray_bubble.h"
 #include "ash/common/system/tray/system_tray_item.h"
 #include "ash/common/system/tray/tray_constants.h"
 #include "ash/common/system/tray/tray_popup_item_container.h"
 #include "ash/shelf/shelf.h"
 #include "ash/shell.h"
 #include "ash/system/status_area_widget.h"
-#include "ash/system/tray/system_tray_bubble.h"
 #include "ash/system/web_notification/web_notification_tray.h"
 #include "ash/test/ash_test_base.h"
 #include "ash/test/status_area_widget_test_helper.h"
 #include "ash/wm/window_util.h"
 #include "base/run_loop.h"
 #include "base/strings/utf_string_conversions.h"
 #include "ui/aura/window.h"
 #include "ui/base/ui_base_types.h"
 #include "ui/compositor/scoped_animation_duration_scale_mode.h"
 #include "ui/events/test/event_generator.h"
@@ skipping 500 matching lines @@
   EXPECT_FALSE(view->active());
 
   generator.set_current_location(move_point);
   generator.ReleaseTouch();
   EXPECT_FALSE(view->active());
 }
 
 TEST_F(SystemTrayTest, SystemTrayHeightWithBubble) {
   SystemTray* tray = GetPrimarySystemTray();
   WebNotificationTray* notification_tray =
-      tray->status_area_widget()->web_notification_tray();
+      StatusAreaWidgetTestHelper::GetStatusAreaWidget()
+          ->web_notification_tray();
 
   // Ensure the initial system tray height is zero.
   EXPECT_EQ(0, notification_tray->system_tray_height_for_test());
 
   // Show the default view, ensure the system tray height is changed.
   tray->ShowDefaultView(BUBBLE_CREATE_NEW);
   RunAllPendingInMessageLoop();
   EXPECT_LT(0, notification_tray->system_tray_height_for_test());
 
   // Hide the default view, ensure the system tray height is back to zero.
   ASSERT_TRUE(tray->CloseSystemBubble());
   RunAllPendingInMessageLoop();
 
   EXPECT_EQ(0, notification_tray->system_tray_height_for_test());
 }
 #endif  // OS_CHROMEOS
 
 }  // namespace test
 }  // namespace ash