cros: Use SessionController to enable system tray settings / notifications tray

ash/session/session_controller.h

Index: ash/session/session_controller.h
diff --git a/ash/session/session_controller.h b/ash/session/session_controller.h
index 975e2185c461e5e85849fc1acc368ac8e5f8accd..afe6222c77fe5c462d459e8ecdfe70eafbc38e0e 100644
--- a/ash/session/session_controller.h
+++ b/ash/session/session_controller.h
@@ -69,6 +69,12 @@ class ASH_EXPORT SessionController
   // Convenience function that returns true if session state is LOGIN_SECONDARY.
   bool IsInSecondaryLoginScreen() const;
 
+  // Returns true if the settings icon should be enabled in the system tray.
+  bool ShouldEnableSettings() const;
+
+  // Returns true if the notification tray should appear.
+  bool ShouldShowNotificationTray() const;
+
   // Gets the ash session state.
   session_manager::SessionState GetSessionState() const;