hbos and hta are already OWNERS of webrtc/stats/ and of rtcstats* files (per-file rtcstats*=) in webrtc/api/. When the webrtc/api/stats/ folder was created we forgot to add this OWNERS file (per-file OWNERS does not apply to subfolders apparently). BUG=chromium:627816 NOTRY=True Review-Url: https://codereview.webrtc.org/2392633002 Cr-Commit-Position: refs/heads/master@{#14482}