[Reland 1] lens overlay: Fix context menu entry point.

The original CL modifies a kombucha test. The modified test fails in
ubsan builds. This appears to be a race condition in kombucha itself, as
kombucha steps run nested by default. This reland takes all the kombucha
steps and flushes events after every step to avoid this
non-deterministic and racy behavior.

> This CL allows us to correctly hook up the CUJ test. This CL prevents
> lens overlay from triggering for non-normal windows.

Bug: 331114227
Change-Id: Ia2043b6df13b3b2eb8353739cae48d12f0ec4a81
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5400496


Reviewed-by: David Pennington <dpenning@chromium.org>
Commit-Queue: Erik Chen <erikchen@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1279061}