This CL can prepare downstream projects for being aware of this new handover state. This was extracted from change 299076. Bug: webrtc:14997 Change-Id: I35bfbe040ffbaa5d7266eb67d58078b66083337a Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/302980 Reviewed-by: Sergey Sukhanov <sergeysu@webrtc.org> Commit-Queue: Victor Boivie <boivie@webrtc.org> Cr-Commit-Position: refs/heads/main@{#39927}