[Spawned off from  https://crbug.com/901363#c5  and  https://crbug.com/901363#c16 ]

cryptohomed calls dbus_g_object_type_install_info() before starting the mount_thread, where it posts the actual request-handling tasks from dbus thread. And then later calls brillo::dbus::RegisterExclusiveService() [through Service::Register == AbstractDbusService::Register].

Double-check when the dbus methods are actually registered on dbus.
If it happens during dbus_g_object_type_install_info(), we may have a race when methods are exposed before cryptohomed is ready to handle them.

(Likely will be obsoleted by refactoring work.)