This prepares for running it in simulated time. TBR=henrika@webrtc.org Bug: webrtc:10465 Change-Id: I9b29b8af9aeba7f0c8209ca77294a63d8068ff1a Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/126481 Reviewed-by: Sebastian Jansson <srte@webrtc.org> Reviewed-by: Oskar Sundbom <ossu@webrtc.org> Cr-Commit-Position: refs/heads/master@{#27083}