ephy_gsb_service_update_thread() and ephy_gsb_service_verify_url_thread() look unsafe
ephy_gsb_service_update_thread() reads and modifies all sorts of shared state without any mutexes. This is a threadsafety problem. Every use of
self needs to be guarded by a mutex, as does all other uses of the same data members throughout the file. We should ensure that it only calls functions that are explicitly marked as safe to be called from the thread. This can be annoying as it requires updating more than just EphyGsbService. E.g. the code calls ephy_gsb_storage_is_operable(). So now EphyGsbStorage needs to be made threadsafe as well.
ephy_gsb_service_verify_url_thread() needs to be checked too.