Triage nag: This Chrome OS bug has an owner but no component. Please add a component so that this can be tracked by the relevant team.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/d45d21dcb78c52143d7044a62c6ae3d0b12be21a

commit d45d21dcb78c52143d7044a62c6ae3d0b12be21a
Author: Scott Violet <sky@chromium.org>
Date: Mon Oct 01 23:31:16 2018

aura: update tests failing with MUS

During the conversion to ws2 a handful of aura unittests got an early out.
This adds comments as to why these tests fail with MUS, and updates one to
work with MUS. For the ones I didn't update I didn't feel fixing the test was
worth it, given we get coverage in the LOCAL case.

BUG= 866502 
TEST=test only changes

Change-Id: If6d1d0bd50c79b727fd9f38c3662312a76ca7d53
Reviewed-on: https://chromium-review.googlesource.com/1256011
Commit-Queue: Scott Violet <sky@chromium.org>
Reviewed-by: Michael Wasserman <msw@chromium.org>
Cr-Commit-Position: refs/heads/master@{#595634}
[modify] https://crrev.com/d45d21dcb78c52143d7044a62c6ae3d0b12be21a/ui/aura/window_event_dispatcher.h
[modify] https://crrev.com/d45d21dcb78c52143d7044a62c6ae3d0b12be21a/ui/aura/window_event_dispatcher_unittest.cc
[modify] https://crrev.com/d45d21dcb78c52143d7044a62c6ae3d0b12be21a/ui/aura/window_unittest.cc

I kept the early outs, but added comments as to why the tests aren't applicable to MUS mode.