Run events_unittests on mac and cast bots.

Mac doesn't have touch UI, and the test doesn't really make too much
sense on cast, but the code under test is built there and the test
is small and fast, so might as well run it. Maybe one day the test
should move to chromium_gtests_for_devices_with_graphical_output instead.

Bug: 843511
Change-Id: I792e8ed5bb419346b23a3e7432a7681e797b244d
Reviewed-on: https://chromium-review.googlesource.com/1129719
Reviewed-by: Kenneth Russell <kbr@chromium.org>
Commit-Queue: Nico Weber <thakis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#573472}
6 files changed