This is a hack to allow `MctUserControls` to be used from `GtkBuilder`
templates, where it’s not possible to pass construct-only properties in
to the `MctUserControls` constructor. It’s not feasible to make
`MctUserControls:dbus-connection` not construct-only, because it gets
used to construct an `MctManager` which then subscribes to various
signals.
So for the cases where `MctUserControls` is used from a builder
template, the code has to connect to the system bus manually, which is
possibly (though unlikely) a blocking operation.
This fixes a critical warning when enabling parental controls in
gnome-initial-setup.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
28992ac7f3