mash: Move SystemTrayImage and TrayImageItem to //ash/common

ash/system/chromeos/tray_tracing.h

 // Copyright 2013 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.
 
 #ifndef ASH_SYSTEM_TRAY_TRACING_H_
 #define ASH_SYSTEM_TRAY_TRACING_H_
 
 #include "ash/ash_export.h"
-#include "ash/system/tray/tray_image_item.h"
+#include "ash/common/system/tray/tray_image_item.h"
 #include "base/macros.h"
 
 namespace views {
 class View;
 }
 
 namespace ash {
 
 class ASH_EXPORT TracingObserver {
  public:
@@ skipping 26 matching lines @@
   void OnTracingModeChanged(bool value) override;
 
   views::View* default_;
 
   DISALLOW_COPY_AND_ASSIGN(TrayTracing);
 };
 
 }  // namespace ash
 
 #endif  // ASH_SYSTEM_TRAY_TRACING_H_