Code review comment for lp://staging/~woodrow-shen/unity-greeter/fix-hidpi-support

You have a lot of hardcoded scaling like:

var hidpi = CairoUtils.check_hidpi_display();
scale = (hidpi) ? 2 : 1;

Why not:
scale = CairoUtils.get_hidpi_scale ()

and just define the 2 once in that function?