Remove chrome/browser/ui/overlay/OWNERS.

This OWNERS file was added temporarily to fix a broken OWNERS
chain. Remove now that we no longer need it.

Part two of a two part fix for c/b/ui/views/overlay/OWNERS.

BUG: 819870
Change-Id: I5f3c280c2a97e504b96f7dbad7331ae930324fed
Reviewed-on: https://chromium-review.googlesource.com/954341Reviewed-by: Elly Fong-Jones <ellyjones@chromium.org>
Commit-Queue: apacible <apacible@chromium.org>
Cr-Commit-Position: refs/heads/master@{#541797}

chrome/browser/ui/overlay/OWNERS

-apacible@chromium.org
\ No newline at end of file