mash: Move StatusTray and StatusAreaWidget to //ash/common

ash/common/system/chromeos/session/tray_session_length_limit_unittest.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/common/system/chromeos/session/tray_session_length_limit.h"
 
-#include "ash/system/tray/system_tray.h"
+#include "ash/common/system/tray/system_tray.h"
 #include "ash/test/ash_test_base.h"
 #include "ash/test/test_system_tray_delegate.h"
 #include "base/time/time.h"
 #include "ui/message_center/message_center.h"
 #include "ui/message_center/notification.h"
 #include "ui/message_center/notification_types.h"
 
 namespace ash {
 namespace test {
 
@@ skipping 129 matching lines @@
   // re-appear and be re-read.
   UpdateSessionLengthLimitInMin(15);
   notification = GetNotification();
   EXPECT_TRUE(notification);
   EXPECT_TRUE(notification->rich_notification_data()
                   .should_make_spoken_feedback_for_popup_updates);
 }
 
 }  // namespace test
 }  // namespace ash