chromeos: Convert system tray session length limit to mojo

ash/system/tray/system_tray_notifier.h

Index: ash/system/tray/system_tray_notifier.h
diff --git a/ash/system/tray/system_tray_notifier.h b/ash/system/tray/system_tray_notifier.h
index 540289838dcfbe9ea32dbc451ca7cac99db710a1..0373448e73340b463c11bee9166753fdc4b0813e 100644
--- a/ash/system/tray/system_tray_notifier.h
+++ b/ash/system/tray/system_tray_notifier.h
@@ -28,7 +28,6 @@ class NetworkObserver;
 class NetworkPortalDetectorObserver;
 class ScreenCaptureObserver;
 class ScreenShareObserver;
-class SessionLengthLimitObserver;
 class StatusAreaFocusObserver;
 class TracingObserver;
 class VirtualKeyboardObserver;
@@ -111,12 +110,6 @@ class ASH_EXPORT SystemTrayNotifier {
                               const base::string16& helper_name);
   void NotifyScreenShareStop();
 
-  // Session length limit.
-  void AddSessionLengthLimitObserver(SessionLengthLimitObserver* observer);
-  void RemoveSessionLengthLimitObserver(SessionLengthLimitObserver* observer);
-  void NotifySessionStartTimeChanged();
-  void NotifySessionLengthLimitChanged();
-
   // Status area focus.
   void AddStatusAreaFocusObserver(StatusAreaFocusObserver* observer);
   void RemoveStatusAreaFocusObserver(StatusAreaFocusObserver* observer);
@@ -145,8 +138,6 @@ class ASH_EXPORT SystemTrayNotifier {
       network_portal_detector_observers_;
   base::ObserverList<ScreenCaptureObserver> screen_capture_observers_;
   base::ObserverList<ScreenShareObserver> screen_share_observers_;
-  base::ObserverList<SessionLengthLimitObserver>
-      session_length_limit_observers_;
   base::ObserverList<StatusAreaFocusObserver> status_area_focus_observers_;
   base::ObserverList<TracingObserver> tracing_observers_;
   base::ObserverList<VirtualKeyboardObserver> virtual_keyboard_observers_;