This had been asked before. But existing answers to not seem to function on newer Gnome 3 versions (I have 3.14.0). Instead the following error message is received:
Error org.freedesktop.DBus.Error.ServiceUnknown: The name org.gnome.ScreenSaver was not provided by any .service files
So, what is the way to unlock Gnome 3 from the command line theses days?