This reverts commit fe53fec24e02d2d644220f913c3f9ae596bbb2d9.
Reason for revert: Speculative revert, may be breaking downstream project
Original change's description:
> [DataChannel] Send and receive packets on the network thread.
>
> This updates sctp channels, including work that happens between the
> data channel controller and the transport, to run on the network
> thread. Previously all network traffic related to data channels was
> routed through the signaling thread before going to either the network
> thread or the caller's thread (e.g. js thread in chrome). Now the
> calls can go straight from the network thread to the JS thread with
> enabling a special flag on the observer (see below) and similarly
> calls to send data, involve 2 threads instead of 3.
>
> * Custom data channel observer adapter implementation that
> maintains compatibility with existing observer implementations in
> that notifications are delivered on the signaling thread.
> The adapter can be explicitly disabled for implementations that
> want to optimize the callback path and promise to not block the
> network thread.
> * Remove the signaling thread copy of data channels in the controller.
> * Remove several PostTask operations that were needed to keep things
> in sync (but the need has gone away).
> * Update tests for the controller to consistently call
> TeardownDataChannelTransport_n to match with production.
> * Update stats collectors (current and legacy) to fetch the data
> channel stats on the network thread where they're maintained.
> * Remove the AsyncChannelCloseTeardown test since the async teardown
> step has gone away.
> * Remove `sid_s` in the channel code since we only need the network
> state now.
> * For the custom observer support (with and without data adapter) and
> maintain compatibility with existing implementations, added a new
> proxy macro that allows an implementation to selectively provide
> its own implementation without being proxied. This is used for
> registering/unregistering a data channel observer.
> * Update the data channel proxy to map most methods to the network
> thread, avoiding the interim jump to the signaling thread.
> * Update a plethora of thread checkers from signaling to network.
>
> Bug: webrtc:11547
> Change-Id: Ib4cff1482e31c46008e187189a79e967389bc518
> Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/299142
> Commit-Queue: Tomas Gunnarsson <tommi@webrtc.org>
> Reviewed-by: Henrik Boström <hbos@webrtc.org>
> Cr-Commit-Position: refs/heads/main@{#39760}
Bug: webrtc:11547
Change-Id: Id0d65594bf727ccea5c49093c942b09714d101ad
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/300341
Auto-Submit: Andrey Logvin <landrey@webrtc.org>
Owners-Override: Andrey Logvin <landrey@webrtc.org>
Bot-Commit: rubber-stamper@appspot.gserviceaccount.com <rubber-stamper@appspot.gserviceaccount.com>
Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org>
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#39764}
7f16fcda0f