Comment 2 for bug 1473764

This should be detected by the OS (gsd?) automatically. Though I agree that an overridable setting might be nice to set `org.gnome.desktop.interface scaling-factor` directly in case the OS gets it wrong. Note that we'd likely have to restart gala after setting this to get it to work right.

Right now applicable values would be 0 (automatic), 1 (lodpi), 2 (pixel-doubled). Displays with a scaling factor of 3 are coming out (4k display on a 12" laptop, for example), but I'm not sure if we want to expose that yet or not.