/etc/X11/Xsession.d/99x11-common_start is in x11-common 1:7.7+13ubuntu3.
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 7 | # $Id: 99x11-common_start 305 2005-07-03 18:51:43Z dnusinow $
# This file is sourced by Xsession(5), not executed.
exec $STARTUP
# vim:set ai et sts=2 sw=2 tw=80:
|