Allow anyone to review public/BUILD.gn.
Allow anyone to review public/BUILD.gn.

This file includes a list of files of the files under public/, which now
has modules/ subdirectories for module-specific headers with different
OWNERS.

Without this rule, public/ OWNERS would still need to review file
additions, while module owners can do anything else without higher-level
OWNERS approval.

BUG=

Review URL: https://codereview.chromium.org/1267733002

git-svn-id: bf5cd6ccde378db821296732a091cfbcf5285fbd@199834 bbb929c8-8fbe-4397-9dbb-9b2b20218538

Pluto-tv/blink-crosswalk,Pluto-tv/blink-crosswalk,Pluto-tv/blink-crosswalk,Pluto-tv/blink-crosswalk,Pluto-tv/blink-crosswalk,Pluto-tv/blink-crosswalk,Pluto-tv/blink-crosswalk,Pluto-tv/blink-crosswalk,Pluto-tv/blink-crosswalk,Pluto-tv/blink-crosswalk