Add Eric as OWNER of subresource_filter component

Change-Id: I35718eeeee57947b54a3e65348af9b1de1ac084c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2354305Reviewed-by: Eric Robinson <ericrobinson@chromium.org>
Reviewed-by: Charlie Harrison <csharrison@chromium.org>
Commit-Queue: Josh Karlin <jkarlin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#798824}

components/subresource_filter/OWNERS

 csharrison@chromium.org
+ericrobinson@chromium.org
 jkarlin@chromium.org
 
 # COMPONENT: UI>Browser>AdFilter