Fix crash when all acks in a feedback message arrive too late.

webrtc/modules/congestion_controller/send_side_congestion_controller.cc

Index: webrtc/modules/congestion_controller/send_side_congestion_controller.cc
diff --git a/webrtc/modules/congestion_controller/send_side_congestion_controller.cc b/webrtc/modules/congestion_controller/send_side_congestion_controller.cc
index e3f84d0e539b5b74ef397fd1255594ee7cc0f0b4..78b7f32ad8bf5e34073f19f79036c9f52e655286 100644
--- a/webrtc/modules/congestion_controller/send_side_congestion_controller.cc
+++ b/webrtc/modules/congestion_controller/send_side_congestion_controller.cc
@@ -240,8 +240,6 @@ void SendSideCongestionController::OnTransportFeedback(
   transport_feedback_adapter_.OnTransportFeedback(feedback);
   std::vector<PacketFeedback> feedback_vector =
       transport_feedback_adapter_.GetTransportFeedbackVector();
-  if (feedback_vector.empty())
-    return;
   DelayBasedBwe::Result result;
   {
     rtc::CritScope cs(&bwe_lock_);