This file is indexed.

/usr/share/unity-control-center/keybindings/50-metacity-system.xml is in metacity-common 1:3.18.3-1ubuntu3.

This file is owned by root:root, with mode 0o777.

It is a symlink to /usr/share/unity-control-center/keybindings/../../gnome-control-center/keybindings/50-metacity-system.xml