This gives assurance that we're not calling any function in cricket::P2PTransportChannel off-thread. Bug: none Change-Id: I21d4e496cf5f301ab85abbd53a5abd4f5068ec39 Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/138271 Commit-Queue: Harald Alvestrand <hta@webrtc.org> Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org> Cr-Commit-Position: refs/heads/master@{#28077}