Add the OWNERS file

BUG=chromium:443539
TEST=None

Change-Id: I121467efc02aa2c007e5707225b1eada6aea5e6a
Reviewed-on: https://chromium-review.googlesource.com/244286
Reviewed-by: Charlie Mooney <charliemooney@chromium.org>
Commit-Queue: Shyh-In Hwang <josephsih@chromium.org>
Tested-by: Shyh-In Hwang <josephsih@chromium.org>