Split VideoReceiveStream2 init into worker / network steps.

This is in preparation for actually doing this initialization
differently in the Call class. This CL takes the registration
steps that are inherently network thread associated and makes
them separate from the ctor/dtor.

Inject Call* instead of worker_thread(), which will simplify upcoming
work that needs to access the network_thread() as well.

This is related to:
https://webrtc-review.googlesource.com/c/src/+/220608
https://webrtc-review.googlesource.com/c/src/+/220609

Bug: webrtc:11993
Change-Id: I72769fd61de84967d9a645750c40d01660a2716b
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/220764
Reviewed-by: Markus Handell <handellm@webrtc.org>
Commit-Queue: Tommi <tommi@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#34172}
diff --git a/audio/audio_receive_stream.cc b/audio/audio_receive_stream.cc
index ef69e73..aecc246 100644
--- a/audio/audio_receive_stream.cc
+++ b/audio/audio_receive_stream.cc
@@ -126,7 +126,7 @@
   RTC_DCHECK(audio_state_);
   RTC_DCHECK(channel_receive_);
 
-  network_thread_checker_.Detach();
+  packet_sequence_checker_.Detach();
 
   RTC_DCHECK(packet_router);
   // Configure bandwidth estimation.
@@ -157,14 +157,14 @@
 
 void AudioReceiveStream::RegisterWithTransport(
     RtpStreamReceiverControllerInterface* receiver_controller) {
-  RTC_DCHECK_RUN_ON(&network_thread_checker_);
+  RTC_DCHECK_RUN_ON(&packet_sequence_checker_);
   RTC_DCHECK(!rtp_stream_receiver_);
   rtp_stream_receiver_ = receiver_controller->CreateReceiver(
       config_.rtp.remote_ssrc, channel_receive_.get());
 }
 
 void AudioReceiveStream::UnregisterFromTransport() {
-  RTC_DCHECK_RUN_ON(&network_thread_checker_);
+  RTC_DCHECK_RUN_ON(&packet_sequence_checker_);
   rtp_stream_receiver_.reset();
 }
 
@@ -395,7 +395,7 @@
 }
 
 void AudioReceiveStream::AssociateSendStream(AudioSendStream* send_stream) {
-  RTC_DCHECK_RUN_ON(&network_thread_checker_);
+  RTC_DCHECK_RUN_ON(&packet_sequence_checker_);
   channel_receive_->SetAssociatedSendChannel(
       send_stream ? send_stream->GetChannel() : nullptr);
   associated_send_stream_ = send_stream;
@@ -416,7 +416,7 @@
 
 const AudioSendStream* AudioReceiveStream::GetAssociatedSendStreamForTesting()
     const {
-  RTC_DCHECK_RUN_ON(&network_thread_checker_);
+  RTC_DCHECK_RUN_ON(&packet_sequence_checker_);
   return associated_send_stream_;
 }