mash: Move system tray cast code into //ash/common

ash/common/system/chromeos/screen_security/screen_tray_item.h

Index: ash/common/system/chromeos/screen_security/screen_tray_item.h
diff --git a/ash/system/chromeos/screen_security/screen_tray_item.h b/ash/common/system/chromeos/screen_security/screen_tray_item.h
similarity index 94%
rename from ash/system/chromeos/screen_security/screen_tray_item.h
rename to ash/common/system/chromeos/screen_security/screen_tray_item.h
index 9452f48044f00e871b7ab402ba0e4602c011f2ca..b670afb256a20306c0004c60a3f9600be502554d 100644
--- a/ash/system/chromeos/screen_security/screen_tray_item.h
+++ b/ash/common/system/chromeos/screen_security/screen_tray_item.h
@@ -2,8 +2,10 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#ifndef ASH_SYSTEM_CHROMEOS_SCREEN_TRAY_ITEM_H_
-#define ASH_SYSTEM_CHROMEOS_SCREEN_TRAY_ITEM_H_
+#ifndef ASH_COMMON_SYSTEM_CHROMEOS_SCREEN_SECURITY_SCREEN_TRAY_ITEM_H_
+#define ASH_COMMON_SYSTEM_CHROMEOS_SCREEN_SECURITY_SCREEN_TRAY_ITEM_H_
+
+#include <string>
 
 #include "ash/common/system/tray/system_tray_item.h"
 #include "ash/common/system/tray/tray_item_view.h"
@@ -133,4 +135,4 @@ class ASH_EXPORT ScreenTrayItem : public SystemTrayItem {
 
 }  // namespace ash
 
-#endif  // ASH_SYSTEM_CHROMEOS_SCREEN_TRAY_ITEM_H_
+#endif  // ASH_COMMON_SYSTEM_CHROMEOS_SCREEN_SECURITY_SCREEN_TRAY_ITEM_H_