mash: Update LoginStatus with session state updates

ash/mus/system_tray_delegate_mus.h

Index: ash/mus/system_tray_delegate_mus.h
diff --git a/ash/mus/system_tray_delegate_mus.h b/ash/mus/system_tray_delegate_mus.h
index 87b189f44523f89b5dea2a97c1c63b7283f99493..ecf464514170c2b2059f0e01e23ecbcdb3262be5 100644
--- a/ash/mus/system_tray_delegate_mus.h
+++ b/ash/mus/system_tray_delegate_mus.h
@@ -17,9 +17,7 @@ class NetworkingConfigDelegate;
 // Handles the settings displayed in the system tray menu. For the classic ash
 // version see SystemTrayDelegateChromeOS.
 //
-// Chrome OS only. Other platforms use DefaultSystemTrayDelegate directly.
-//
-// TODO: Support all methods in SystemTrayDelegate. http://crbug.com/647412.
+// TODO: Replace with SystemTrayController. http://crbug.com/647412.
 class SystemTrayDelegateMus : public DefaultSystemTrayDelegate {
  public:
   SystemTrayDelegateMus();
@@ -27,6 +25,7 @@ class SystemTrayDelegateMus : public DefaultSystemTrayDelegate {
 
  private:
   // SystemTrayDelegate:
+  LoginStatus GetUserLoginStatus() const override;
   NetworkingConfigDelegate* GetNetworkingConfigDelegate() const override;
 
   std::unique_ptr<NetworkingConfigDelegate> networking_config_delegate_;