Refactor MainThreadSchedulerImpl tests.

Bug: 841735
Change-Id: Ieb6b6c2be0347ae67004ac62645ed303a3748a9f
Reviewed-on: https://chromium-review.googlesource.com/1080551
Reviewed-by: Alexander Timin <altimin@chromium.org>
Reviewed-by: Sami Kyöstilä <skyostil@chromium.org>
Commit-Queue: Greg Kraynov <kraynov@chromium.org>
Cr-Commit-Position: refs/heads/master@{#563620}
1 file changed