Pass time constant to bwe smoothing filter.

webrtc/modules/congestion_controller/delay_based_bwe.h

Index: webrtc/modules/congestion_controller/delay_based_bwe.h
diff --git a/webrtc/modules/congestion_controller/delay_based_bwe.h b/webrtc/modules/congestion_controller/delay_based_bwe.h
index 0f1472e6729dbb976887caf30731d209af9a42a0..c5a599f334c65d9c14c8ae0169dfe0558a9f9e79 100644
--- a/webrtc/modules/congestion_controller/delay_based_bwe.h
+++ b/webrtc/modules/congestion_controller/delay_based_bwe.h
@@ -20,6 +20,7 @@
 #include "webrtc/base/rate_statistics.h"
 #include "webrtc/base/thread_checker.h"
 #include "webrtc/modules/congestion_controller/probe_bitrate_estimator.h"
+#include "webrtc/modules/congestion_controller/probing_interval_estimator.h"
 #include "webrtc/modules/congestion_controller/trendline_estimator.h"
 #include "webrtc/modules/remote_bitrate_estimator/aimd_rate_control.h"
 #include "webrtc/modules/remote_bitrate_estimator/include/remote_bitrate_estimator.h"
@@ -51,6 +52,7 @@ class DelayBasedBwe {
   bool LatestEstimate(std::vector<uint32_t>* ssrcs,
                       uint32_t* bitrate_bps) const;
   void SetMinBitrate(int min_bitrate_bps);
+  int64_t GetProbingIntervalMs() const;
 
  private:
   // Computes a bayesian estimate of the throughput given acks containing
@@ -99,6 +101,7 @@ class DelayBasedBwe {
   double trendline_smoothing_coeff_;
   double trendline_threshold_gain_;
   const bool in_trendline_experiment_;
+  ProbingIntervalEstimator probing_interval_estimator_;
 
   RTC_DISALLOW_IMPLICIT_CONSTRUCTORS(DelayBasedBwe);
 };