Edit the file

	/etc/pam.d/gdm

Add the following lines

auth    optional    pam_keyring.so try_first_pass
session optional    pam_keyring.so

The order in which this lines are placed in this file are important, Here is a copy from my system

#%PAM-1.0
auth       required    pam_env.so
auth       optional    pam_keyring.so try_first_pass <---
auth       include     system-auth
account    required    pam_nologin.so
account    include     system-auth
password   include     system-auth
session    optional    pam_keyinit.so force revoke
session    include     system-auth
session    required    pam_loginuid.so
session    optional    pam_console.so
session    optional    pam_keyring.so <---