This patch make CreateOffer/CreateAnswer use the ice credentials
of pooled sessions (if any).
BUG=webrtc:9807
Change-Id: I51e0578f2ff0d4faa93d9666bd6b2c15461e8985
Reviewed-on: https://webrtc-review.googlesource.com/c/102923
Reviewed-by: Qingsi Wang <qingsi@webrtc.org>
Reviewed-by: Steve Anton <steveanton@webrtc.org>
Commit-Queue: Jonas Oreland <jonaso@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#25132}
