Configuration file for keyboard list at login screen in RHEL 7 ( gnome 3.8)

Hi,
I am trying to find out configuration file which stores keyboards displayed at login screen (gdm) in RHEL 7.

I am able to add keyboards through Settings->Region & Languages->Login Screen.
But not able to find the file where this keyboards are stored.

I also found out the keyboard list for gnome-session (after logging in), keyboards are stored in
org.gnome.desktop.input-sources souces.

But where is the list of keyboard, at login screen, is stored? (configuration file or gsettings path).