Also remove test code that can cause leaks into production. Add sequence checkers. Bug: webrtc:11988 Change-Id: I67b4cec6ee77d73ccffbbc88c9081ebb3c3cc423 Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/185503 Commit-Queue: Tommi <tommi@webrtc.org> Reviewed-by: Karl Wiberg <kwiberg@webrtc.org> Cr-Commit-Position: refs/heads/master@{#32228}