tablet: Fix cases carrying over snapped windows from laptop to tablet.

When identifying snapped windows to carry over to split view on entering
tablet mode, ignore the app list, non user positionable windows (such as
extension popups), windows being dragged, and windows hidden from
overview.

Test: ash_unittests TabletModeControllerTest.*
Bug: 931859
Change-Id: Ib498fb6c5ebad5ac907d05f1e4448e9ba4c254b7
Reviewed-on: https://chromium-review.googlesource.com/c/1471456
Commit-Queue: Avery Musbach <amusbach@chromium.org>
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#636508}
2 files changed