We use a significant amount of code duplication in our draw
validation, that we can consolidate.

BUG=angle:571

Change-Id: I96787cbddf00d9289e368456fb85079d8acec513
Reviewed-on: https://chromium-review.googlesource.com/202975Reviewed-by: Shannon Woods <shannonwoods@chromium.org>
Tested-by: Jamie Madill <jmadill@chromium.org>