* Change data channel creation code to return RTCError for more
detailed/accurate errors.
* Move DataChannelController::sid_allocator_ to the network thread.
* Add a temporary duplicate vector of channels on the network thread.
This will eventually be the main vector.
* Delete one test that turns out to be racy (as long as we're using
both the signaling and network threads).
Bug: webrtc:11547, webrtc:12796
Change-Id: I93ab721a09872d075046a907df60e8aee4263371
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/298624
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Commit-Queue: Tomas Gunnarsson <tommi@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#39719}