*re-land with fix for Chromium compile*

This saves us from needing to replicate the same code in two places.

BUG=angleproject:956

Change-Id: I68dffee715df03bd25685e3ed5c0506ffc41c3b9
Reviewed-on: https://chromium-review.googlesource.com/263258Tested-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>
Reviewed-by: Brandon Jones <bajones@chromium.org>