This reverts commit c48ad732d6eb69f14dd6d44f801d62997cef2c2f.
Reason for revert: breaks downstream project
Original change's description:
> Don't create channel_manager when media_engine is not set
>
> Also remove a bunch of functions in ChannelManager that were just
> forwarding to MediaEngineInterface.
>
> Bug: webrtc:13931
> Change-Id: Ia38591fd22c665cace16d032f5c1e384e413cded
> Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/261304
> Reviewed-by: Tomas Gunnarsson <tommi@webrtc.org>
> Reviewed-by: Henrik Boström <hbos@webrtc.org>
> Commit-Queue: Harald Alvestrand <hta@webrtc.org>
> Cr-Commit-Position: refs/heads/main@{#36801}
Bug: webrtc:13931
Change-Id: I1e260a2489547bd9483b50e043c28d2805b0fa5a
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/261660
Commit-Queue: Artem Titov <titovartem@webrtc.org>
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Owners-Override: Artem Titov <titovartem@webrtc.org>
Bot-Commit: rubber-stamper@appspot.gserviceaccount.com <rubber-stamper@appspot.gserviceaccount.com>
Cr-Commit-Position: refs/heads/main@{#36811}
c6c02efb56