/usr/share/upstart/sessions/unity-panel-service-lockscreen.conf is in unity-services 7.2.2+14.04.20140714-0ubuntu1.1.
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 8 | description "Backing Service for the Unity Panel"
author "Andrea Azzarone <andrea.azzarone@canonical.com>"
start on desktop-lock
stop on desktop-unlock
respawn
exec /usr/lib/unity/unity-panel-service --lockscreen-mode
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