Relanding "Pass time constant to bwe smoothing filter."

webrtc/modules/congestion_controller/probing_interval_estimator.h

 /*
  *  Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
 #ifndef WEBRTC_MODULES_CONGESTION_CONTROLLER_PROBING_INTERVAL_ESTIMATOR_H_
 #define WEBRTC_MODULES_CONGESTION_CONTROLLER_PROBING_INTERVAL_ESTIMATOR_H_
 
 #include "webrtc/base/constructormagic.h"
 #include "webrtc/base/optional.h"
 #include "webrtc/modules/remote_bitrate_estimator/aimd_rate_control.h"
 
 namespace webrtc {
 
 class ProbingIntervalEstimator {
  public:
   explicit ProbingIntervalEstimator(const AimdRateControl* aimd_rate_control);
 
-  ProbingIntervalEstimator(int min_interval_ms,
-                           int max_interval_ms,
+  ProbingIntervalEstimator(int64_t min_interval_ms,
+                           int64_t max_interval_ms,
+                           int64_t default_interval_ms,
                            const AimdRateControl* aimd_rate_control);
-  rtc::Optional<int> GetIntervalMs() const;
+  int64_t GetIntervalMs() const;
 
  private:
-  const int min_interval_ms_;
-  const int max_interval_ms_;
+  const int64_t min_interval_ms_;
+  const int64_t max_interval_ms_;
+  const int64_t default_interval_ms_;
   const AimdRateControl* const aimd_rate_control_;
   RTC_DISALLOW_COPY_AND_ASSIGN(ProbingIntervalEstimator);
 };
 
 }  // namespace webrtc
 #endif  // WEBRTC_MODULES_CONGESTION_CONTROLLER_PROBING_INTERVAL_ESTIMATOR_H_