mash: Migrate remaining tray observers and notify functions.

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

Index: ash/common/system/chromeos/session/session_length_limit_observer.h
diff --git a/ash/system/chromeos/session/session_length_limit_observer.h b/ash/common/system/chromeos/session/session_length_limit_observer.h
similarity index 71%
rename from ash/system/chromeos/session/session_length_limit_observer.h
rename to ash/common/system/chromeos/session/session_length_limit_observer.h
index 54aba7fb9b4aaa565606ce4554098c558023fcd0..d46a25373eddf80808eb91b4ba602b5a806a8ffe 100644
--- a/ash/system/chromeos/session/session_length_limit_observer.h
+++ b/ash/common/system/chromeos/session/session_length_limit_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_CHROMEOS_SESSION_SESSION_LENGTH_LIMIT_OBSERVER_H_
-#define ASH_SYSTEM_CHROMEOS_SESSION_SESSION_LENGTH_LIMIT_OBSERVER_H_
+#ifndef ASH_COMMON_SYSTEM_CHROMEOS_SESSION_SESSION_LENGTH_LIMIT_OBSERVER_H_
+#define ASH_COMMON_SYSTEM_CHROMEOS_SESSION_SESSION_LENGTH_LIMIT_OBSERVER_H_
 
 #include "ash/ash_export.h"
 
@@ -23,4 +23,4 @@ class ASH_EXPORT SessionLengthLimitObserver {
 
 }  // namespace ash
 
-#endif  // ASH_SYSTEM_CHROMEOS_SESSION_SESSION_LENGTH_LIMIT_OBSERVER_H_
+#endif  // ASH_COMMON_SYSTEM_CHROMEOS_SESSION_SESSION_LENGTH_LIMIT_OBSERVER_H_