This method returns the DTLS SSL certificate chain associated with the audio transport on the remote side. This will become populated once the DTLS connection with the peer has been completed. TBR=deadbeef@webrtc.org Bug: webrtc:8800 Change-Id: Ib90ccb3463415e798c17c187c5bdbfc4da26f11f Reviewed-on: https://webrtc-review.googlesource.com/44140 Commit-Queue: Zhi Huang <zhihuang@webrtc.org> Reviewed-by: Taylor Brandstetter <deadbeef@webrtc.org> Cr-Commit-Position: refs/heads/master@{#21785}