Fix touch coordinate mapping in Windows

Coordinates were not previously being mapped correctly from screen
coordinates to window coordinates.

Bug: skia:
Change-Id: Ie56ac3b42273aede6f97ee6f83ac9766020510ea
Reviewed-on: https://skia-review.googlesource.com/109109
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Chris Dalton <csmartdalton@google.com>
1 file changed