This is a reland of d181ee798da57ce5b955f09e8dcb755fba70b51b
Original change's description:
> Adds peer scenario connection interface.
>
> This allows implementing custom clients for test in peer connection
> scenario tests. For example server side behavior.
>
> Bug: webrtc:10839
> Change-Id: I5627b7a4d967d401f31d2e9a8f861d0849eb0184
> Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/151907
> Commit-Queue: Sebastian Jansson <srte@webrtc.org>
> Reviewed-by: Per Kjellander <perkj@webrtc.org>
> Cr-Commit-Position: refs/heads/master@{#29125}
TBR=perkj@webrtc.org
Bug: webrtc:10839
Change-Id: I5e0857dc7647587eab2a9b61965f627bf310b88c
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/152481
Reviewed-by: Sebastian Jansson <srte@webrtc.org>
Commit-Queue: Sebastian Jansson <srte@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#29147}
47287d546d