RTCPeerConnection.ontrack event added.

content/renderer/media/rtc_peer_connection_handler.cc

Index: content/renderer/media/rtc_peer_connection_handler.cc
diff --git a/content/renderer/media/rtc_peer_connection_handler.cc b/content/renderer/media/rtc_peer_connection_handler.cc
index 1fb95e1bceb7114a4ff9657bf0fa29063e3b206e..45170bdefb8c207d042d0d4a334e29a2908667e2 100644
--- a/content/renderer/media/rtc_peer_connection_handler.cc
+++ b/content/renderer/media/rtc_peer_connection_handler.cc
@@ -1682,6 +1682,7 @@ RTCPeerConnectionHandler::GetReceivers() {
         track_adapter =
             track_adapter_map_->GetRemoteTrackAdapter(webrtc_track->id());
     DCHECK(track_adapter);
+    DCHECK(track_adapter->is_initialized());
     // Create a reference to the receiver. Multiple |RTCRtpReceiver|s can
     // reference the same webrtc track, see |id|.
     web_receivers.push_back(base::MakeUnique<RTCRtpReceiver>(
@@ -1951,8 +1952,58 @@ void RTCPeerConnectionHandler::OnAddStream(
 
   track_metrics_.AddStream(MediaStreamTrackMetrics::RECEIVED_STREAM,
                            stream_ptr->webrtc_stream().get());
-  if (!is_closed_)
-    client_->DidAddRemoteStream(stream_ptr->webkit_stream());
+  if (!is_closed_) {
+    // Get receivers for the tracks in this stream. The result is a subset of
+    // |RTCPeerConnectionHandler::GetReceivers|. We can't invoke that here
+    // because creating receivers for remote streams that have not been
+    // processed on both threads yet might grab track adapters that have not
+    // been initialized yet.
+    // TODO(hbos): Helper function instead of duplicate code!
+    std::vector<rtc::scoped_refptr<webrtc::RtpReceiverInterface>>
+        webrtc_receivers = native_peer_connection_->GetReceivers();
+    std::vector<std::unique_ptr<blink::WebRTCRtpReceiver>> stream_web_receivers;
+    for (auto& webrtc_receiver : webrtc_receivers) {
+      rtc::scoped_refptr<webrtc::MediaStreamTrackInterface> webrtc_track =
+          webrtc_receiver->track();
+      DCHECK(webrtc_track);
+      bool is_stream_receiver = false;
+      if (webrtc_track->kind() ==
+          webrtc::MediaStreamTrackInterface::kAudioKind) {
+        for (const auto& track :
+             stream_ptr->webrtc_stream()->GetAudioTracks()) {
+          if (webrtc_track == track) {
+            is_stream_receiver = true;
+            break;
+          }
+        }
+      } else {
+        for (const auto& track :
+             stream_ptr->webrtc_stream()->GetVideoTracks()) {
+          if (webrtc_track == track) {
+            is_stream_receiver = true;
+            break;
+          }
+        }
+      }
+      if (is_stream_receiver) {
+        std::unique_ptr<WebRtcMediaStreamTrackAdapterMap::AdapterRef>
+            track_adapter =
+                track_adapter_map_->GetRemoteTrackAdapter(webrtc_track->id());
+        DCHECK(track_adapter);
+        DCHECK(track_adapter->is_initialized());
+        // Create a reference to the receiver. Multiple |RTCRtpReceiver|s can
+        // reference the same webrtc track, see |id|.
+        stream_web_receivers.push_back(base::MakeUnique<RTCRtpReceiver>(
+            webrtc_receiver.get(), std::move(track_adapter)));
+      }
+    }
+    blink::WebVector<std::unique_ptr<blink::WebRTCRtpReceiver>> result(
+        stream_web_receivers.size());
+    for (size_t i = 0; i < stream_web_receivers.size(); ++i) {
+      result[i] = std::move(stream_web_receivers[i]);
+    }
+    client_->DidAddRemoteStream(stream_ptr->webkit_stream(), &result);
+  }
 }
 
 void RTCPeerConnectionHandler::OnRemoveStream(