Resize preview for correct clipping

Before, the remote view for the widget in launcher is reused to generate a new preview. However, measuring the view without changing the scale would cause strange clippings. This CL sets the scale of the widget views by manually computing the size ratio.

Change ag/19572297 is necessary before a complete clean-up.

Test: Create a weather widget on first screen -> go to Wallpaper & style -> App grid -> tap on a different grid and verify that the clipping is correct
Fix: 228328759
Change-Id: I8242d3bcfcf30ec924552c1320e22f8a3592f1c1