GitLab

- Remove some structure that was previously necessary for Cocoa browser
- the visibility lock controller is vestigial: we release the lock,
but never acquire it

Bug: 1063417
Change-Id: I55ccc6b14b0ffed7d81beb640a54ec8b1110e831
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2117321Reviewed-by: Elly Fong-Jones <ellyjones@chromium.org>
Commit-Queue: Leonard Grey <lgrey@chromium.org>
Cr-Commit-Position: refs/heads/master@{#753211}