/usr/share/xul-ext/gdata-provider/defaults/preferences/000system.js is in xul-ext-gdata-provider 1.3+build1-0ubuntu1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /etc/xul-ext/gdata-provider.js
/etc/xul-ext/gdata-provider.js