Relanding "Pass time constant to bwe smoothing filter."

webrtc/modules/congestion_controller/transport_feedback_adapter.cc

Index: webrtc/modules/congestion_controller/transport_feedback_adapter.cc
diff --git a/webrtc/modules/congestion_controller/transport_feedback_adapter.cc b/webrtc/modules/congestion_controller/transport_feedback_adapter.cc
index 46639067c283cf0667e38957aaff29476d2414cb..7756fee365da2dd872be36bf028e525480b5abe3 100644
--- a/webrtc/modules/congestion_controller/transport_feedback_adapter.cc
+++ b/webrtc/modules/congestion_controller/transport_feedback_adapter.cc
@@ -73,6 +73,11 @@ void TransportFeedbackAdapter::SetMinBitrate(int min_bitrate_bps) {
   delay_based_bwe_->SetMinBitrate(min_bitrate_bps);
 }
 
+int64_t TransportFeedbackAdapter::GetProbingIntervalMs() const {
+  rtc::CritScope cs(&bwe_lock_);
+  return delay_based_bwe_->GetProbingIntervalMs();
+}
+
 std::vector<PacketInfo> TransportFeedbackAdapter::GetPacketFeedbackVector(
     const rtcp::TransportFeedback& feedback) {
   int64_t timestamp_us = feedback.GetBaseTimeUs();