GitLab

In chasing a bug I decided to restructure things slightly, including adding
some CHECKs. I don't expect this to impact anything.

BUG=867035
TEST=none

Change-Id: I86bf2d672d886a3944607bbba053e79769d43351
Reviewed-on: https://chromium-review.googlesource.com/c/1278814Reviewed-by: Sadrul Chowdhury <sadrul@chromium.org>
Commit-Queue: Scott Violet <sky@chromium.org>
Cr-Commit-Position: refs/heads/master@{#599657}