Instead of using SetAlive on the old flag (which might allow old tasks in the queue to run). Bug: webrtc:12339 Change-Id: Ia1a3eb6932f62881f013fd62b0e008d97d8713cd Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/211863 Reviewed-by: Tommi <tommi@webrtc.org> Reviewed-by: Danil Chapovalov <danilchap@webrtc.org> Commit-Queue: Niels Moller <nisse@webrtc.org> Cr-Commit-Position: refs/heads/master@{#33475}