[MediaStream] Construct track adapter lazily in MediaStreamVideoSource

This is a preparation CL to make GetWeakPtr() pure virtual.
Since creating the track adapter requires a weak pointer to the source,
it will not be possible to create it in the source constructor when
GetWeakPtr becomes virtual.

Bug: 1158227
Change-Id: I480d22da45632aacb227776c326a9f00135215f4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2588908Reviewed-by: Elad Alon <eladalon@chromium.org>
Commit-Queue: Guido Urdaneta <guidou@chromium.org>
Cr-Commit-Position: refs/heads/master@{#837064}

third_party/blink/public/web/modules/mediastream/media_stream_video_source.h

@@ -309,6 +309,7 @@ class BLINK_MODULES_EXPORT MediaStreamVideoSource
   void DidStopSource(RestartResult result);
   void NotifyCapturingLinkSecured(size_t num_encoded_sinks);
   size_t CountEncodedSinks() const;
+  scoped_refptr<VideoTrackAdapter> GetTrackAdapter();
 
   State state_;
 

third_party/blink/renderer/modules/mediastream/media_stream_video_source.cc

@@ -43,10 +43,7 @@ MediaStreamVideoSource* MediaStreamVideoSource::GetVideoSource(
   return static_cast<MediaStreamVideoSource*>(source->GetPlatformSource());
 }
 
-MediaStreamVideoSource::MediaStreamVideoSource() : state_(NEW) {
-  track_adapter_ = base::MakeRefCounted<VideoTrackAdapter>(
-      Platform::Current()->GetIOTaskRunner(), GetWeakPtr());
-}
+MediaStreamVideoSource::MediaStreamVideoSource() : state_(NEW) {}
 
 MediaStreamVideoSource::~MediaStreamVideoSource() {
   DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);
@@ -79,10 +76,10 @@ void MediaStreamVideoSource::AddTrack(
       state_ = STARTING;
       StartSourceImpl(
           ConvertToBaseRepeatingCallback(CrossThreadBindRepeating(
-              &VideoTrackAdapter::DeliverFrameOnIO, track_adapter_)),
+              &VideoTrackAdapter::DeliverFrameOnIO, GetTrackAdapter())),
           ConvertToBaseRepeatingCallback(CrossThreadBindRepeating(
               &VideoTrackAdapter::DeliverEncodedVideoFrameOnIO,
-              track_adapter_)));
+              GetTrackAdapter())));
       break;
     }
     case STARTING:
@@ -127,7 +124,7 @@ void MediaStreamVideoSource::RemoveTrack(MediaStreamVideoTrack* video_track,
 
   // Call |frame_adapter_->RemoveTrack| here even if adding the track has
   // failed and |frame_adapter_->AddCallback| has not been called.
-  track_adapter_->RemoveTrack(video_track);
+  GetTrackAdapter()->RemoveTrack(video_track);
 
   if (tracks_.empty()) {
     if (callback) {
@@ -191,7 +188,7 @@ void MediaStreamVideoSource::DidStopSource(RestartResult result) {
 void MediaStreamVideoSource::ReconfigureTrack(
     MediaStreamVideoTrack* track,
     const VideoTrackAdapterSettings& adapter_settings) {
-  track_adapter_->ReconfigureTrack(track, adapter_settings);
+  GetTrackAdapter()->ReconfigureTrack(track, adapter_settings);
   // It's OK to reconfigure settings even if ReconfigureTrack fails, provided
   // |track| is not connected to a different source, which is a precondition
   // for calling this method.
@@ -209,13 +206,13 @@ void MediaStreamVideoSource::StopForRestart(RestartCallback callback,
   }
 
   DCHECK(!restart_callback_);
-  track_adapter_->StopFrameMonitoring();
+  GetTrackAdapter()->StopFrameMonitoring();
   state_ = STOPPING_FOR_RESTART;
   restart_callback_ = std::move(callback);
 
   if (send_black_frame) {
     const base::Optional<gfx::Size> source_size =
-        track_adapter_->source_frame_size();
+        GetTrackAdapter()->source_frame_size();
     scoped_refptr<media::VideoFrame> black_frame =
         media::VideoFrame::CreateBlackFrame(
             source_size.has_value() ? *source_size
@@ -223,7 +220,7 @@ void MediaStreamVideoSource::StopForRestart(RestartCallback callback,
     PostCrossThreadTask(
         *io_task_runner(), FROM_HERE,
         CrossThreadBindOnce(&VideoTrackAdapter::DeliverFrameOnIO,
-                            track_adapter_, black_frame,
+                            GetTrackAdapter(), black_frame,
                             base::TimeTicks::Now()));
   }
 
@@ -336,7 +333,7 @@ void MediaStreamVideoSource::SetDeviceRotationDetection(bool enabled) {
 
 base::SingleThreadTaskRunner* MediaStreamVideoSource::io_task_runner() const {
   DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);
-  return track_adapter_->io_task_runner();
+  return Platform::Current()->GetIOTaskRunner().get();
 }
 
 base::Optional<media::VideoCaptureFormat>
@@ -388,7 +385,7 @@ void MediaStreamVideoSource::DoStopSource() {
   DVLOG(3) << "DoStopSource()";
   if (state_ == ENDED)
     return;
-  track_adapter_->StopFrameMonitoring();
+  GetTrackAdapter()->StopFrameMonitoring();
   StopSourceImpl();
   state_ = ENDED;
   SetReadyState(WebMediaStreamSource::kReadyStateEnded);
@@ -432,7 +429,7 @@ void MediaStreamVideoSource::FinalizeAddPendingTracks() {
     }
 
     if (result == mojom::blink::MediaStreamRequestResult::OK) {
-      track_adapter_->AddTrack(
+      GetTrackAdapter()->AddTrack(
           track_info.track, track_info.frame_callback,
           track_info.encoded_frame_callback, track_info.settings_callback,
           track_info.format_callback, *track_info.adapter_settings);
@@ -457,9 +454,9 @@ void MediaStreamVideoSource::StartFrameMonitoring() {
   base::Optional<media::VideoCaptureFormat> current_format = GetCurrentFormat();
   double frame_rate = current_format ? current_format->frame_rate : 0.0;
   if (current_format && enable_device_rotation_detection_) {
-    track_adapter_->SetSourceFrameSize(current_format->frame_size);
+    GetTrackAdapter()->SetSourceFrameSize(current_format->frame_size);
   }
-  track_adapter_->StartFrameMonitoring(
+  GetTrackAdapter()->StartFrameMonitoring(
       frame_rate, WTF::BindRepeating(&MediaStreamVideoSource::SetMutedState,
                                      weak_factory_.GetWeakPtr()));
 }
@@ -513,6 +510,15 @@ VideoCaptureFeedbackCB MediaStreamVideoSource::GetFeedbackCallback() const {
   return base::DoNothing();
 }
 
+scoped_refptr<VideoTrackAdapter> MediaStreamVideoSource::GetTrackAdapter() {
+  DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);
+  if (!track_adapter_) {
+    track_adapter_ =
+        base::MakeRefCounted<VideoTrackAdapter>(io_task_runner(), GetWeakPtr());
+  }
+  return track_adapter_;
+}
+
 MediaStreamVideoSource::PendingTrackInfo::PendingTrackInfo(
     MediaStreamVideoTrack* track,
     const VideoCaptureDeliverFrameCB& frame_callback,