[webrtc-pc] Pull Request: Clarify `RTCRtpContributingSource` and `RTCRtpSynchronizationSource`.

chxg has just submitted a new pull request for https://github.com/w3c/webrtc-pc:

== Clarify `RTCRtpContributingSource` and `RTCRtpSynchronizationSource`. ==
Fixes: #2172

See https://github.com/w3c/webrtc-pc/pull/2190

Received on Friday, 26 April 2019 10:23:56 UTC