Add the ChromeOS trybot to the CQ config. BUG=angleproject:1347 Change-Id: I93266da474909352a4b83de52cffde82687bda86 Reviewed-on: https://chromium-review.googlesource.com/346735 Commit-Queue: Jamie Madill <jmadill@chromium.org> Reviewed-by: Jamie Madill <jmadill@chromium.org>