As per spec.

R=ahaas@chromium.org

Change-Id: I46d4bdd444452fef05c234688c27aad8d086bf61
Reviewed-on: https://chromium-review.googlesource.com/663457Reviewed-by: Andreas Haas <ahaas@chromium.org>
Commit-Queue: Andreas Rossberg <rossberg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#47973}