Revert "chromeos: Move files in //ash/common to //ash, part 1"

ash/common/system/user/user_observer.h

Index: ash/common/system/user/user_observer.h
diff --git a/ash/system/user/user_observer.h b/ash/common/system/user/user_observer.h
similarity index 76%
rename from ash/system/user/user_observer.h
rename to ash/common/system/user/user_observer.h
index 64c2b9de40f60b5d6c8d0a68e4aa4ba1fd0696f0..8c30606fa010e545e7a0dea6fbe77e2bea7b0042 100644
--- a/ash/system/user/user_observer.h
+++ b/ash/common/system/user/user_observer.h
@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#ifndef ASH_SYSTEM_USER_USER_OBSERVER_H_
-#define ASH_SYSTEM_USER_USER_OBSERVER_H_
+#ifndef ASH_COMMON_SYSTEM_USER_USER_OBSERVER_H_
+#define ASH_COMMON_SYSTEM_USER_USER_OBSERVER_H_
 
 #include "ash/ash_export.h"
 
@@ -22,4 +22,4 @@ class ASH_EXPORT UserObserver {
 
 }  // namespace ash
 
-#endif  // ASH_SYSTEM_USER_USER_OBSERVER_H_
+#endif  // ASH_COMMON_SYSTEM_USER_USER_OBSERVER_H_