This prepares for reusing the driver logic for correctness testing.

NOTRY=true

Bug: chromium:866862
Change-Id: If901ca8552cf48f29e240ed5b52ea7e722e0e1e4
Reviewed-on: https://chromium-review.googlesource.com/1163608
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Reviewed-by: Sergiy Byelozyorov <sergiyb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#54961}