GitLab

The present CL follows up after [1] about overview not stealing focus
from a window snapped in split view. The present CL makes the solution
simpler and less error prone.

[1] https://chromium-review.googlesource.com/c/chromium/src/+/1756550

Test: ash_unittests TabletModeControllerTest.StartSplitViewAndThenOverview
Bug: 993403
Change-Id: I9c25fbdfa8fd63050769817e1e2b4380389bd015
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1768833Reviewed-by: Ahmed Fakhry <afakhry@chromium.org>
Commit-Queue: Avery Musbach <amusbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#691881}