Reland "Use non-proxied source object in VideoTrack."

This is a reland of 3eb29c12358930a60134f185cd849e0d12aa9166

This reland doesn't contain the AudioTrack changes (see original
description) that got triggered in some cases and needs to be
addressed separately.

Original change's description:
> Use non-proxied source object in VideoTrack.
>
> Use the internal representation of the video source object from the
> track. Before there were implicit thread hops due to use of the proxy.
>
> Also, override AudioTrack's enabled methods to enforce thread
> expectations.
>
> Bug: webrtc:13540
> Change-Id: I4bc7aca96d6fc24f31ade45e47f52599f1cc2f97
> Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/250180
> Reviewed-by: Harald Alvestrand <hta@webrtc.org>
> Commit-Queue: Tomas Gunnarsson <tommi@webrtc.org>
> Cr-Commit-Position: refs/heads/main@{#35911}

Bug: webrtc:13540
Change-Id: I59997be174cc9278e3e5910d493efd5352e6de68
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/250940
Auto-Submit: 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@{#35924}

pc/BUILD.gn

@@ -903,6 +903,7 @@ rtc_library("video_track") {
     "../api:sequence_checker",
     "../api/video:video_frame",
     "../media:rtc_media_base",
+    "../pc:rtc_pc_base",
     "../rtc_base",
     "../rtc_base:checks",
     "../rtc_base:refcount",

pc/media_stream_track_proxy.h

@@ -29,12 +29,12 @@ BYPASS_PROXY_CONSTMETHOD0(std::string, kind)
 BYPASS_PROXY_CONSTMETHOD0(std::string, id)
 PROXY_CONSTMETHOD0(TrackState, state)
 PROXY_CONSTMETHOD0(bool, enabled)
+PROXY_METHOD1(bool, set_enabled, bool)
 BYPASS_PROXY_CONSTMETHOD0(AudioSourceInterface*, GetSource)
 PROXY_METHOD1(void, AddSink, AudioTrackSinkInterface*)
 PROXY_METHOD1(void, RemoveSink, AudioTrackSinkInterface*)
 PROXY_METHOD1(bool, GetSignalLevel, int*)
 PROXY_METHOD0(rtc::scoped_refptr<AudioProcessorInterface>, GetAudioProcessor)
-PROXY_METHOD1(bool, set_enabled, bool)
 PROXY_METHOD1(void, RegisterObserver, ObserverInterface*)
 PROXY_METHOD1(void, UnregisterObserver, ObserverInterface*)
 END_PROXY_MAP(AudioTrack)
@@ -43,7 +43,7 @@ BEGIN_PROXY_MAP(VideoTrack)
 PROXY_PRIMARY_THREAD_DESTRUCTOR()
 BYPASS_PROXY_CONSTMETHOD0(std::string, kind)
 BYPASS_PROXY_CONSTMETHOD0(std::string, id)
-PROXY_SECONDARY_CONSTMETHOD0(TrackState, state)
+PROXY_CONSTMETHOD0(TrackState, state)
 PROXY_SECONDARY_CONSTMETHOD0(bool, enabled)
 PROXY_SECONDARY_METHOD1(bool, set_enabled, bool)
 PROXY_SECONDARY_CONSTMETHOD0(ContentHint, content_hint)

pc/video_rtp_receiver.cc

@@ -41,11 +41,7 @@ VideoRtpReceiver::VideoRtpReceiver(
       track_(VideoTrackProxyWithInternal<VideoTrack>::Create(
           rtc::Thread::Current(),
           worker_thread,
-          VideoTrack::Create(receiver_id,
-                             CreateVideoTrackSourceProxy(rtc::Thread::Current(),
-                                                         worker_thread,
-                                                         source_),
-                             worker_thread))),
+          VideoTrack::Create(receiver_id, source_, worker_thread))),
       attachment_id_(GenerateUniqueId()) {
   RTC_DCHECK(worker_thread_);
   SetStreams(streams);

pc/video_track.cc

@@ -22,12 +22,14 @@
 
 namespace webrtc {
 
-VideoTrack::VideoTrack(const std::string& label,
-                       VideoTrackSourceInterface* video_source,
+VideoTrack::VideoTrack(
+    const std::string& label,
+    rtc::scoped_refptr<
+        VideoTrackSourceProxyWithInternal<VideoTrackSourceInterface>> source,
     rtc::Thread* worker_thread)
     : MediaStreamTrack<VideoTrackInterface>(label),
       worker_thread_(worker_thread),
-      video_source_(video_source),
+      video_source_(std::move(source)),
       content_hint_(ContentHint::kNone) {
   RTC_DCHECK_RUN_ON(&signaling_thread_);
   // Detach the thread checker for VideoSourceBaseGuarded since we'll make calls
@@ -54,18 +56,18 @@ void VideoTrack::AddOrUpdateSink(rtc::VideoSinkInterface<VideoFrame>* sink,
   VideoSourceBaseGuarded::AddOrUpdateSink(sink, wants);
   rtc::VideoSinkWants modified_wants = wants;
   modified_wants.black_frames = !enabled();
-  video_source_->AddOrUpdateSink(sink, modified_wants);
+  video_source_->internal()->AddOrUpdateSink(sink, modified_wants);
 }
 
 void VideoTrack::RemoveSink(rtc::VideoSinkInterface<VideoFrame>* sink) {
   RTC_DCHECK_RUN_ON(worker_thread_);
   VideoSourceBaseGuarded::RemoveSink(sink);
-  video_source_->RemoveSink(sink);
+  video_source_->internal()->RemoveSink(sink);
 }
 
 void VideoTrack::RequestRefreshFrame() {
   RTC_DCHECK_RUN_ON(worker_thread_);
-  video_source_->RequestRefreshFrame();
+  video_source_->internal()->RequestRefreshFrame();
 }
 
 VideoTrackSourceInterface* VideoTrack::GetSource() const {
@@ -88,10 +90,11 @@ void VideoTrack::set_content_hint(ContentHint hint) {
 
 bool VideoTrack::set_enabled(bool enable) {
   RTC_DCHECK_RUN_ON(worker_thread_);
+  auto* source = video_source_->internal();
   for (auto& sink_pair : sink_pairs()) {
     rtc::VideoSinkWants modified_wants = sink_pair.wants;
     modified_wants.black_frames = !enable;
-    video_source_->AddOrUpdateSink(sink_pair.sink, modified_wants);
+    source->AddOrUpdateSink(sink_pair.sink, modified_wants);
   }
   return MediaStreamTrack<VideoTrackInterface>::set_enabled(enable);
 }
@@ -102,28 +105,29 @@ bool VideoTrack::enabled() const {
 }
 
 MediaStreamTrackInterface::TrackState VideoTrack::state() const {
-  RTC_DCHECK_RUN_ON(worker_thread_);
+  RTC_DCHECK_RUN_ON(&signaling_thread_);
   return MediaStreamTrack<VideoTrackInterface>::state();
 }
 
 void VideoTrack::OnChanged() {
   RTC_DCHECK_RUN_ON(&signaling_thread_);
-  worker_thread_->Invoke<void>(
-      RTC_FROM_HERE, [this, state = video_source_->state()]() {
-        // TODO(tommi): Calling set_state() this way isn't ideal since we're
-        // currently blocking the signaling thread and set_state() may
-        // internally fire notifications via `FireOnChanged()` which may further
-        // amplify the blocking effect on the signaling thread.
+  auto* source = video_source_->internal();
+  auto state = source->state();
   rtc::Thread::ScopedDisallowBlockingCalls no_blocking_calls;
   set_state(state == MediaSourceInterface::kEnded ? kEnded : kLive);
-      });
 }
 
 rtc::scoped_refptr<VideoTrack> VideoTrack::Create(
     const std::string& id,
     VideoTrackSourceInterface* source,
     rtc::Thread* worker_thread) {
-  return rtc::make_ref_counted<VideoTrack>(id, source, worker_thread);
+  rtc::scoped_refptr<
+      VideoTrackSourceProxyWithInternal<VideoTrackSourceInterface>>
+      source_proxy = VideoTrackSourceProxy::Create(rtc::Thread::Current(),
+                                                   worker_thread, source);
+
+  return rtc::make_ref_counted<VideoTrack>(id, std::move(source_proxy),
+                                           worker_thread);
 }
 
 }  // namespace webrtc

pc/video_track.h

@@ -21,6 +21,7 @@
 #include "api/video/video_sink_interface.h"
 #include "api/video/video_source_interface.h"
 #include "media/base/video_source_base.h"
+#include "pc/video_track_source_proxy.h"
 #include "rtc_base/thread.h"
 #include "rtc_base/thread_annotations.h"
 
@@ -49,8 +50,10 @@ class VideoTrack : public MediaStreamTrack<VideoTrackInterface>,
   std::string kind() const override;
 
  protected:
-  VideoTrack(const std::string& id,
-             VideoTrackSourceInterface* video_source,
+  VideoTrack(
+      const std::string& id,
+      rtc::scoped_refptr<
+          VideoTrackSourceProxyWithInternal<VideoTrackSourceInterface>> source,
       rtc::Thread* worker_thread);
   ~VideoTrack();
 
@@ -60,7 +63,10 @@ class VideoTrack : public MediaStreamTrack<VideoTrackInterface>,
 
   RTC_NO_UNIQUE_ADDRESS webrtc::SequenceChecker signaling_thread_;
   rtc::Thread* const worker_thread_;
-  const rtc::scoped_refptr<VideoTrackSourceInterface> video_source_;
+  const rtc::scoped_refptr<
+      VideoTrackSourceProxyWithInternal<VideoTrackSourceInterface>>
+      video_source_;
+
   ContentHint content_hint_ RTC_GUARDED_BY(worker_thread_);
 };