This is a companion issue to webrtc:9605. Specifically, the implementation of mDNS responder in Chromium is intended to be a browser service that further utilizes the service provided by the network stack for mDNS transactions. The motivation of introducing the mDNS stack to WebRTC and Chromium is detailed as follows.

WebRTC currently exposes the private IP addresses of endpoints (via ICE candidate gathering) to applications in an attempt to establish a direct peer-to-peer link and increase the probability of successful connection between the endpoints. The ICE gathering process and the signaling of these private addresses as host candidates have strong privacy implications (e.g. browser fingerprinting) but are however often performed without user consent. 

In the Internet-Draft (draft-mdns-ice-candidates-00), using mDNS to obfuscate the private IP addresses of endpoints is proposed as a privacy measure to amend the current ICE candidate gathering behavior.

We intend to implement this feature for WebRTC (in Chromium), enabling IP handling modes defined in the Internet Draft (draft-ietf-rtcweb-ip-handling-09) and also new modes beyond the definition therein.

This bug tracks the related changes in the Chromium codebase.