Do not activate fakeOmnibox when omnibox is focused.

Activating voiceover on fakeOmnibox if omnibox is focused will prevent
user from using the real omnibox.

Bug: 1248893
Change-Id: I75f0d53e4e63262f09a42b1b0f6677a4c08ec0db
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3172632


Auto-Submit: Olivier Robin <olivierrobin@chromium.org>
Reviewed-by: Gauthier Ambard <gambard@chromium.org>
Commit-Queue: Olivier Robin <olivierrobin@chromium.org>
Cr-Commit-Position: refs/heads/main@{#923345}