/etc/xdg/autostart/devilspie.desktop is in ubuntu-mobile-default-settings 0.12.
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 | [Desktop Entry]
Name=DevilsPie
Comment=Force fullscreen undecorated windows
Exec=devilspie /etc/devilspie.cfg
Terminal=false
Type=Application
X-GNOME-Autostart-enabled=true
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