GitLab

Make it use DeleteDelegate() to be more consistent with
StatusAreaWidgetDelegate. Defer closing the widget until all the
top-level windows are closed.

Bug: 628655
Test: ash_unittests
Change-Id: I066b45dab9c848b8f990f7fb51f0170e5e66a861
Reviewed-on: https://chromium-review.googlesource.com/907390
Commit-Queue: James Cook <jamescook@chromium.org>
Reviewed-by: Michael Wasserman <msw@chromium.org>
Cr-Commit-Position: refs/heads/master@{#540550}