This is a reland of 3ed36c0521546881656c73984456485dcab16205
Original change's description:
> Reland "Remove `stopped_` from AudioRtpReceiver and VideoRtpReceiver."
>
> This is a reland of bb57e2d7aa9b36843233d1394422f03d12d9c31f
>
> The difference from the original CL is that a check for
> `state_ == kLive` inside of RemoteAudioSource::AddSink has been removed.
> This caused a side effect that registering the sink while the source
> was in an "initializing" state, failed. The last remaining state
> however, is `kEnded` - but since there's no logic in the class around
> the expected value of the states, the check inside of AddSink()
> doesn't provide an additional value - it's rather a surprise for
> developers if it doesn't succeed. So, now removed.
>
> Original change's description:
> > Remove `stopped_` from AudioRtpReceiver and VideoRtpReceiver.
> >
> > This simplifies the logic in these classes a bit, which makes upcoming
> > change easier. The `stopped_` flag in these classes was essentially
> > the same thing as `media_channel_ == nullptr`, which is what's
> > consistently used now for the same checks.
> >
> > Bug: webrtc:13540
> > Change-Id: Ib60bfad9f28d5ddee8a8d5170c3f2a7ef017a5ca
> > Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/250163
> > Reviewed-by: Harald Alvestrand <hta@webrtc.org>
> > Commit-Queue: Tomas Gunnarsson <tommi@webrtc.org>
> > Cr-Commit-Position: refs/heads/main@{#35907}
>
> Bug: webrtc:13540
> Change-Id: I3e5b3046fae11cb56b50c38c5f08972a6f283dd5
> Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/251326
> Auto-Submit: Tomas Gunnarsson <tommi@webrtc.org>
> Commit-Queue: Tomas Gunnarsson <tommi@webrtc.org>
> Reviewed-by: Harald Alvestrand <hta@webrtc.org>
> Commit-Queue: Harald Alvestrand <hta@webrtc.org>
> Cr-Commit-Position: refs/heads/main@{#35958}
Bug: webrtc:13540
Change-Id: I6d7d67fddb1ddfc69a302f0f69a9b815f2fd82f7
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/251386
Reviewed-by: Tomas Gunnarsson <tommi@webrtc.org>
Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#35967}
20d8d9150c