This can be updated in several places. Also adds a test which covers
some of the paths.

Bug: angleproject:2746
Change-Id: Id119e527fd0064998d7ad5011a9d8376e7b9dab0
Reviewed-on: https://chromium-review.googlesource.com/1153569
Commit-Queue: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>