In preparation for adding RFC8888 support. Bug: webrtc:42225697 Change-Id: I15ab535d36c70b982243b84d76da25f1b613a766 Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/366421 Commit-Queue: Per Kjellander <perkj@webrtc.org> Reviewed-by: Danil Chapovalov <danilchap@webrtc.org> Cr-Commit-Position: refs/heads/main@{#43287}