The SDES key exchange mechanism for WebRTC has been declared a MUST NOT in the relevant IETF standards since 2013. The SDES specification has been declared Historic by the IETF. Its usage in Chrome has declined significantly over the recent year. This intent is to deprecate and remove this code from Chromium and WebRTC.
The reason why SDES is deprecated is that it is a security problem: It exposes session keys to Javascript, which means that entities with access to the negotiation exchange, or with the ability to subvert the Javascript, can decrypt the media sent over the connection.