This CL adds the sequence checks to the functions that creates or destroys the encoder context. Those functions must be executed on the webrtc encoder sequence. Bug: b/320555128 Change-Id: I1daa93f2f5326073e8d75e1d711d7554bed76a62 Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/356460 Reviewed-by: Erik Språng <sprang@webrtc.org> Commit-Queue: Hirokazu Honda <hiroh@google.com> Cr-Commit-Position: refs/heads/main@{#42612}