This prevents having to have sdp_offer_answer depend on peer_connection
for the messaging functions.
Bug: webrtc:11995
Change-Id: Icad7c9c0e6149bd1b8d78e37eff5f9786b74692e
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/186662
Reviewed-by: Henrik Boström <hbos@webrtc.org>
Commit-Queue: Harald Alvestrand <hta@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#32310}