Revert "Preparation for ReceiveStatisticsProxy lock reduction."

This reverts commit 24eed2735b2135227bcfefbabf34a89f9a5fec99.

Reason for revert: Speculative revert: breaks downstream project

Original change's description:
> Preparation for ReceiveStatisticsProxy lock reduction.
> 
> Update tests to call VideoReceiveStream::GetStats() in the same or at
> least similar way it gets called in production (construction thread,
> same TQ/thread).
> 
> Mapped out threads and context for ReceiveStatisticsProxy,
> VideoQualityObserver and VideoReceiveStream. Added
> follow-up TODOs for webrtc:11489.
> 
> One functional change in ReceiveStatisticsProxy is that when sender
> side RtcpPacketTypesCounterUpdated calls are made, the counter is
> updated asynchronously since the sender calls the method on a different
> thread than the receiver.
> 
> Make CallClient::SendTask public to allow tests to run tasks in the
> right context. CallClient already does this internally for GetStats.
> 
> Remove 10 sec sleep in StopSendingKeyframeRequestsForInactiveStream.
> 
> Bug: webrtc:11489
> Change-Id: Ib45bfc59d8472e9c5ea556e6ecf38298b8f14921
> Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/172847
> Commit-Queue: Tommi <tommi@webrtc.org>
> Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
> Reviewed-by: Magnus Flodman <mflodman@webrtc.org>
> Cr-Commit-Position: refs/heads/master@{#31008}

TBR=mbonadei@webrtc.org,henrika@webrtc.org,kwiberg@webrtc.org,tommi@webrtc.org,juberti@webrtc.org,mflodman@webrtc.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: webrtc:11489
Change-Id: I48b8359cdb791bf22b1a2c2c43d46263b01e0d65
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/173082
Reviewed-by: Artem Titov <titovartem@webrtc.org>
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#31023}
diff --git a/test/scenario/stats_collection_unittest.cc b/test/scenario/stats_collection_unittest.cc
index af3b982..fae3365 100644
--- a/test/scenario/stats_collection_unittest.cc
+++ b/test/scenario/stats_collection_unittest.cc
@@ -25,26 +25,17 @@
       VideoStreamConfig::Encoder::Implementation::kSoftware;
   config.hooks.frame_pair_handlers = {analyzer->Handler()};
   auto* caller = s->CreateClient("caller", CallClientConfig());
-  auto* callee = s->CreateClient("callee", CallClientConfig());
   auto route =
-      s->CreateRoutes(caller, {s->CreateSimulationNode(network_config)}, callee,
+      s->CreateRoutes(caller, {s->CreateSimulationNode(network_config)},
+                      s->CreateClient("callee", CallClientConfig()),
                       {s->CreateSimulationNode(NetworkSimulationConfig())});
-  VideoStreamPair* video = s->CreateVideoStream(route->forward(), config);
+  auto* video = s->CreateVideoStream(route->forward(), config);
   auto* audio = s->CreateAudioStream(route->forward(), AudioStreamConfig());
   s->Every(TimeDelta::Seconds(1), [=] {
     collectors->call.AddStats(caller->GetStats());
-    collectors->video_send.AddStats(video->send()->GetStats(), s->Now());
     collectors->audio_receive.AddStats(audio->receive()->GetStats());
-
-    // Querying the video stats from within the expected runtime environment
-    // (i.e. the TQ that belongs to the CallClient, not the Scenario TQ that
-    // we're currently on).
-    VideoReceiveStream::Stats video_receive_stats;
-    auto* video_stream = video->receive();
-    callee->SendTask([&video_stream, &video_receive_stats]() {
-      video_receive_stats = video_stream->GetStats();
-    });
-    collectors->video_receive.AddStats(video_receive_stats);
+    collectors->video_send.AddStats(video->send()->GetStats(), s->Now());
+    collectors->video_receive.AddStats(video->receive()->GetStats());
   });
 }
 }  // namespace