/usr/share/gnome-session/sessions/openbox-gnome.session is in openbox-gnome-session 3.6.1-1ubuntu2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 | [GNOME Session]
Name=GNOME/Openbox
RequiredComponents=openbox;gnome-settings-daemon;gnome-panel;nautilus-classic;gnome-flashback-services
DesktopName=GNOME
|