/usr/share/pam-configs/gnome-keyring is in libpam-gnome-keyring 3.18.3-0ubuntu2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
| 1 2 3 4 5 6 | Name: GNOME Keyring Daemon - Login keyring management
Default: yes
Priority: 0
Password-Type: Additional
Password-Final:
	optional	pam_gnome_keyring.so
 |