The WebRTC getStats API is specified in https://w3c.github.io/webrtc-stats/ and allows querying information about the current state of a RTCPeerConnection API and some of its member objects.
When adding a new standardized RTCStatsMember it is necessary to add
it to the Chrome allowlist
chrome/test/data/webrtc/peerconnection_getstats.js
before landing the WebRTC change. This mechanism prevents the accidential
addition and exposure of non-standard attributes and is not required for
RTCNonStandardStatsMember which is not exposed to the web API.