/usr/share/glib-2.0/schemas/ubuntu-defaults-nexus7-powerbtn.gschema.override is in ubuntu-defaults-nexus7 0.54.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 | [org.gnome.settings-daemon.plugins.power]
button-power='suspend'
|