The workaround in https://webrtc-review.googlesource.com/c/src/+/367740 is incomplete because it does not fix the issue for the first decoded mono packet after CN/PLC. This CL extends the workaround to such a case and adds a unit test for it. Note: it was verified that the 2nd packet after CN/PLC is trivial stereo. Credits: jakobi@webrtc.org for raising the concern Bug: webrtc:376493209 Change-Id: Ide27e411781693f14629cf9db8b6c0c0fc762a17 Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/368160 Reviewed-by: Jakob Ivarsson <jakobi@webrtc.org> Commit-Queue: Alessio Bazzica <alessiob@webrtc.org> Cr-Commit-Position: refs/heads/main@{#43393}