Added implementation of four functions in the BBR congestion controller.

webrtc/modules/remote_bitrate_estimator/test/estimators/min_rtt_filter.h

 /*
  *  Copyright (c) 2017 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_REMOTE_BITRATE_ESTIMATOR_TEST_ESTIMATORS_MIN_RTT_FILTER_H_
 #define WEBRTC_MODULES_REMOTE_BITRATE_ESTIMATOR_TEST_ESTIMATORS_MIN_RTT_FILTER_H_
 
-#include <climits>
-#include <map>
-#include <memory>
-#include <utility>
-#include <vector>
-
-#include "webrtc/logging/rtc_event_log/mock/mock_rtc_event_log.h"
-#include "webrtc/modules/remote_bitrate_estimator/include/send_time_history.h"
-#include "webrtc/modules/remote_bitrate_estimator/test/bwe.h"
-
 namespace webrtc {
 namespace testing {
 namespace bwe {
 class MinRttFilter {
  public:
   MinRttFilter();
   ~MinRttFilter();
   int64_t min_rtt();
   void UpdateMinRtt(int64_t min_rtt);
 
-  // Checks whether or last discovered min_rtt value
-  // is older than x seconds.
+  // Checks whether or not last discovered min_rtt value is older than x
+  // seconds.
   bool MinRttExpired(int64_t now);
   void set_min_rtt_discovery_time(int64_t discovery_time);
 };
 }  // namespace bwe
 }  // namespace testing
 }  // namespace webrtc
 
 #endif  // WEBRTC_MODULES_REMOTE_BITRATE_ESTIMATOR_TEST_ESTIMATORS_MIN_RTT_FILTER_H_