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

ash/common/system/chromeos/session/last_window_closed_observer.h

Index: ash/common/system/chromeos/session/last_window_closed_observer.h
diff --git a/ash/system/session/last_window_closed_observer.h b/ash/common/system/chromeos/session/last_window_closed_observer.h
similarity index 63%
rename from ash/system/session/last_window_closed_observer.h
rename to ash/common/system/chromeos/session/last_window_closed_observer.h
index e23e5da69e06cfa25391cdcbd27068da0ada98ad..c19df95a495142567e0b18f66294e1d9744ed7fb 100644
--- a/ash/system/session/last_window_closed_observer.h
+++ b/ash/common/system/chromeos/session/last_window_closed_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_SESSION_LAST_WINDOW_CLOSED_OBSERVER_H_
-#define ASH_SYSTEM_SESSION_LAST_WINDOW_CLOSED_OBSERVER_H_
+#ifndef ASH_COMMON_SYSTEM_CHROMEOS_SESSION_LAST_WINDOW_CLOSED_OBSERVER_H_
+#define ASH_COMMON_SYSTEM_CHROMEOS_SESSION_LAST_WINDOW_CLOSED_OBSERVER_H_
 
 #include "ash/ash_export.h"
 
@@ -19,4 +19,4 @@ class ASH_EXPORT LastWindowClosedObserver {
 
 }  // namespace ash
 
-#endif  // ASH_SYSTEM_SESSION_LAST_WINDOW_CLOSED_OBSERVER_H_
+#endif  // ASH_COMMON_SYSTEM_CHROMEOS_SESSION_LAST_WINDOW_CLOSED_OBSERVER_H_