GitLab

When starting a managed guest session (with no Terms of Service), a
blank Ash dialog is shown for a brief moment before the session starts.
This is caused by the Ash dialog for Oobe being shown even when all the
Oobe screens are skipped.

This CL changes the behavior of the Ash dialog to only show when
required by using a OobeUI::Observer. The dialog is not shown by
default, and will be shown when a Oobe screen is shown.

OobeScreenWaiter now checks that the native window is visible by
default. A small number of tests had to be changed to either show the
native window or ignore the visibility check. The reasoning for the
changes are in the comments for their respective tests.

The WebUI behavior is unchanged.

Bug: 1000164
Change-Id: I9995f4beba85d7c5af7b13f81f1a654e2d52f372
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1790450
Commit-Queue: Jit Yao Yap <jityao@google.com>
Reviewed-by: Denis Kuznetsov <antrim@chromium.org>
Cr-Commit-Position: refs/heads/master@{#697539}