In preparation for making them robust.

BUG=chromium:648135

Change-Id: I88fc87d8887064fda04087c56de05d8725a6fe5f
Reviewed-on: https://chromium-review.googlesource.com/387469Reviewed-by: Geoff Lang <geofflang@chromium.org>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>