Keep running_ state in sync with active layers.

When layers are activated/deactivated via UpdateActiveSimulcastLayers,
the flag wasn't being updated. This resulted in calls to Stop() getting
ignored after an implicit start via activating layers.

Bug: chromium:1234779
Change-Id: I4a72e624874526d27d3e97d6903112367c5e77fb
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/227700
Reviewed-by: Magnus Flodman <mflodman@webrtc.org>
Commit-Queue: Tommi <tommi@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#34654}

call/video_send_stream.h

@@ -218,6 +218,15 @@ class VideoSendStream {
   // When a stream is stopped, it can't receive, process or deliver packets.
   virtual void Stop() = 0;
 
+  // Accessor for determining if the stream is active. This is an inexpensive
+  // call that must be made on the same thread as `Start()` and `Stop()` methods
+  // are called on and will return `true` iff activity has been started either
+  // via `Start()` or `UpdateActiveSimulcastLayers()`. If activity is either
+  // stopped or is in the process of being stopped as a result of a call to
+  // either `Stop()` or `UpdateActiveSimulcastLayers()` where all layers were
+  // deactivated, the return value will be `false`.
+  virtual bool started() = 0;
+
   // If the resource is overusing, the VideoSendStream will try to reduce
   // resolution or frame rate until no resource is overusing.
   // TODO(https://crbug.com/webrtc/11565): When the ResourceAdaptationProcessor

media/engine/fake_webrtc_call.h

@@ -196,6 +196,7 @@ class FakeVideoSendStream final
       const std::vector<bool> active_layers) override;
   void Start() override;
   void Stop() override;
+  bool started() override { return IsSending(); }
   void AddAdaptationResource(
       rtc::scoped_refptr<webrtc::Resource> resource) override;
   std::vector<rtc::scoped_refptr<webrtc::Resource>> GetAdaptationResources()

video/video_send_stream.cc

@@ -186,10 +186,16 @@ void VideoSendStream::UpdateActiveSimulcastLayers(
     const std::vector<bool> active_layers) {
   RTC_DCHECK_RUN_ON(&thread_checker_);
 
+  // Keep our `running_` flag expected state in sync with active layers since
+  // the `send_stream_` will be implicitly stopped/started depending on the
+  // state of the layers.
+  bool running = false;
+
   rtc::StringBuilder active_layers_string;
   active_layers_string << "{";
   for (size_t i = 0; i < active_layers.size(); ++i) {
     if (active_layers[i]) {
+      running = true;
       active_layers_string << "1";
     } else {
       active_layers_string << "0";
@@ -202,10 +208,17 @@ void VideoSendStream::UpdateActiveSimulcastLayers(
   RTC_LOG(LS_INFO) << "UpdateActiveSimulcastLayers: "
                    << active_layers_string.str();
 
-  rtp_transport_queue_->PostTask(
-      ToQueuedTask(transport_queue_safety_, [this, active_layers] {
+  rtp_transport_queue_->PostTask(ToQueuedTask(
+      transport_queue_safety_, [this, active_layers, was_running = running_] {
         send_stream_.UpdateActiveSimulcastLayers(active_layers);
+        const bool running = rtp_video_sender_->IsActive();
+        if (was_running != running) {
+          running ? transport_queue_safety_->SetAlive()
+                  : transport_queue_safety_->SetNotAlive();
+        }
       }));
+
+  running_ = running;
 }
 
 void VideoSendStream::Start() {
@@ -241,6 +254,11 @@ void VideoSendStream::Stop() {
   }));
 }
 
+bool VideoSendStream::started() {
+  RTC_DCHECK_RUN_ON(&thread_checker_);
+  return running_;
+}
+
 void VideoSendStream::AddAdaptationResource(
     rtc::scoped_refptr<Resource> resource) {
   RTC_DCHECK_RUN_ON(&thread_checker_);

video/video_send_stream.h

@@ -78,6 +78,7 @@ class VideoSendStream : public webrtc::VideoSendStream {
       const std::vector<bool> active_layers) override;
   void Start() override;
   void Stop() override;
+  bool started() override;
 
   void AddAdaptationResource(rtc::scoped_refptr<Resource> resource) override;
   std::vector<rtc::scoped_refptr<Resource>> GetAdaptationResources() override;
@@ -94,8 +95,6 @@ class VideoSendStream : public webrtc::VideoSendStream {
  private:
   friend class test::VideoSendStreamPeer;
 
-  class ConstructionTask;
-
   absl::optional<float> GetPacingFactorOverride() const;
 
   RTC_NO_UNIQUE_ADDRESS SequenceChecker thread_checker_;
@@ -110,7 +109,7 @@ class VideoSendStream : public webrtc::VideoSendStream {
   const VideoEncoderConfig::ContentType content_type_;
   std::unique_ptr<VideoStreamEncoderInterface> video_stream_encoder_;
   EncoderRtcpFeedback encoder_feedback_;
-  RtpVideoSenderInterface* const rtp_video_sender_ = nullptr;
+  RtpVideoSenderInterface* const rtp_video_sender_;
   VideoSendStreamImpl send_stream_;
   bool running_ RTC_GUARDED_BY(thread_checker_) = false;
 };

video/video_send_stream_tests.cc

@@ -2251,6 +2251,8 @@ TEST_F(VideoSendStreamTest, VideoSendStreamUpdateActiveSimulcastLayers) {
 
              CreateVideoStreams();
 
+             EXPECT_FALSE(GetVideoSendStream()->started());
+
              // Inject a frame, to force encoder creation.
              GetVideoSendStream()->Start();
              GetVideoSendStream()->SetSource(&forwarder,
@@ -2264,6 +2266,7 @@ TEST_F(VideoSendStreamTest, VideoSendStreamUpdateActiveSimulcastLayers) {
   // which in turn updates the VideoEncoder's bitrate.
   SendTask(RTC_FROM_HERE, task_queue(), [this]() {
     GetVideoSendStream()->UpdateActiveSimulcastLayers({true, true});
+    EXPECT_TRUE(GetVideoSendStream()->started());
   });
   EXPECT_TRUE(encoder.WaitBitrateChanged(true));
 
@@ -2280,6 +2283,7 @@ TEST_F(VideoSendStreamTest, VideoSendStreamUpdateActiveSimulcastLayers) {
   GetVideoEncoderConfig()->simulcast_layers[1].active = false;
   SendTask(RTC_FROM_HERE, task_queue(), [this]() {
     GetVideoSendStream()->UpdateActiveSimulcastLayers({false, false});
+    EXPECT_FALSE(GetVideoSendStream()->started());
   });
   EXPECT_TRUE(encoder.WaitBitrateChanged(false));