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

ash/system/tray/default_system_tray_delegate.cc

Index: ash/system/tray/default_system_tray_delegate.cc
diff --git a/ash/system/tray/default_system_tray_delegate.cc b/ash/system/tray/default_system_tray_delegate.cc
index da18b14acbf360573e296b22992f48cb3d1050ca..fa8bfd968701875bfa3bf63e31267a88fc3aa783 100644
--- a/ash/system/tray/default_system_tray_delegate.cc
+++ b/ash/system/tray/default_system_tray_delegate.cc
@@ -26,12 +26,4 @@ bool DefaultSystemTrayDelegate::IsUserSupervised() const {
   return GetUserLoginStatus() == LoginStatus::SUPERVISED;
 }
 
-bool DefaultSystemTrayDelegate::ShouldShowSettings() const {
-  return true;
-}
-
-bool DefaultSystemTrayDelegate::ShouldShowNotificationTray() const {
-  return true;
-}
-
 }  // namespace ash