cbui views: add pbos to OWNERS

Bug: None
Change-Id: I5efda82d931dee0c6da98e17d68240a10f5eb885
Reviewed-on: https://chromium-review.googlesource.com/c/1337791Reviewed-by: Elly Fong-Jones <ellyjones@chromium.org>
Reviewed-by: Bret Sepulveda <bsep@chromium.org>
Commit-Queue: Bret Sepulveda <bsep@chromium.org>
Cr-Commit-Position: refs/heads/master@{#608476}

chrome/browser/ui/views/OWNERS

@@ -4,6 +4,7 @@ bsep@chromium.org
 ellyjones@chromium.org
 kylixrd@chromium.org
 msw@chromium.org
+pbos@chromium.org
 pkasting@chromium.org
 sky@chromium.org