flags: set OWNERS for flag-metadata.json

Everyone will be editing this file and I don't want to destroy the c/b OWNERS'
review queue. Setting the OWNERS to myself and avi@ (aka "flags-team").

Bug: 897809
Change-Id: Ifc0afe1cea365f7398cfb14f5f4556f9bdeb818e
Reviewed-on: https://chromium-review.googlesource.com/c/1340519Reviewed-by: Nico Weber <thakis@chromium.org>
Reviewed-by: Avi Drissman <avi@chromium.org>
Commit-Queue: Elly Fong-Jones <ellyjones@chromium.org>
Cr-Commit-Position: refs/heads/master@{#608801}

chrome/browser/OWNERS

@@ -69,6 +69,9 @@ per-file chrome_webusb_browser_client*=rockot@google.com
 
 per-file exo_parts.*=reveman@chromium.org
 
+per-file flag-metadata.json=avi@chromium.org
+per-file flag-metadata.json=ellyjones@chromium.org
+
 per-file io_thread*=mmenke@chromium.org
 per-file io_thread*=rch@chromium.org
 per-file io_thread*=rsleevi@chromium.org