Reduce the argument count to make future refactorings easier.

BUG=angleproject:754

Change-Id: Ia8acfc2bc8f922ad6a115e198ea51a62710a422c
Reviewed-on: https://chromium-review.googlesource.com/307873Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Tryjob-Request: Jamie Madill <jmadill@chromium.org>
Tested-by: Jamie Madill <jmadill@chromium.org>