Grit: Make unit tests run on the trybots

Prevent tests from getting into a failed state on various OSes, by
running the tests on the bots instead of only as a presubmit.

Tests take a few seconds locally on Linux and Windows.

Bug: 961359
Change-Id: I71fabf230d611de5cd06380832085558521de83d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1614698
Reviewed-by: Dirk Pranke <dpranke@chromium.org>
Reviewed-by: Lei Zhang <thestig@chromium.org>
Reviewed-by: Marc-Antoine Ruel <maruel@chromium.org>
Commit-Queue: Rebekah Potter <rbpotter@chromium.org>
Cr-Commit-Position: refs/heads/master@{#662917}
10 files changed