Prevent accessing more arguments than provided. BUG=390111 Change-Id: Iecc2ac2354a82cca937a823e5c588c662264e36c Reviewed-on: https://chromium-review.googlesource.com/213551 Tested-by: Nicolas Capens <capn@chromium.org> Reviewed-by: Jamie Madill <jmadill@chromium.org>