[reland] chromeos: removes usage of ui/aura/mus from a number of places

With mash/window-service going away none of this code is used anymore.

BUG=958245
TEST=covered by tests

Change-Id: I25abe23426e090c18b21288f19a90e2403e88d06
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1613973
Reviewed-by: Jun Mukai <mukai@chromium.org>
Commit-Queue: Scott Violet <sky@chromium.org>
Cr-Commit-Position: refs/heads/master@{#660386}
24 files changed