The function finish_cb can be called as a result of a call to ca_context_cancel
in cancelled_cb. This will result in a deadlock because, as per documentation,
g_cancellable_disconnect cannot be called inside the cancellable handler.
It is possible to detect if the call to finish_cb is caused by ca_context_cancel
checking if error_code == CA_ERROR_CANCELED. To avoid the deadlock we should
call g_signal_handler_disconnect instead g_cancellable_disconnect if this is the
case.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/474
This is a simple libcanberra abstraction object, so we are able
to play file/theme sounds without poking into GTK+/X11. Play
requests are delegated to a separate thread, so we don't block
UI on cards that are slow to wake up from power saving.
