create OWNERS file for chromium version of libyuv

BUG=none
TEST=none
R=dingkai@google.com, parisa@chromium.org

Review URL: https://webrtc-codereview.appspot.com/1646004

git-svn-id: http://libyuv.googlecode.com/svn/trunk@722 16f28f9a-4ce2-e073-06de-1de4eb20be90

OWNERS

+fbarchard@chromium.org
+mflodman@chromium.org
+