/usr/lib/xulrunner-addons/plugins/gxineplugin.so is in gxineplugin 0.5.908-3.1ubuntu1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/xulrunner-addons/plugins/../../gxine/gxineplugin.so
/usr/lib/xulrunner-addons/plugins/../../gxine/gxineplugin.so