/usr/share/gconf/defaults/10_mutter-common is in mutter-common 3.4.1-0ubuntu1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 | /desktop/gnome/keybindings/custom0/action x-terminal-emulator
/desktop/gnome/keybindings/custom0/binding <Primary><Alt>t
/desktop/gnome/keybindings/custom0/name "Launch Terminal"
|