Make the acceptable queue in the cwnd experiment configurable.

webrtc/modules/congestion_controller/include/send_side_congestion_controller.h

 /*
  *  Copyright (c) 2012 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.
  */
 
@@ skipping 142 matching lines @@
   int64_t last_reported_rtt_ GUARDED_BY(network_state_lock_);
   NetworkState network_state_ GUARDED_BY(network_state_lock_);
   bool pause_pacer_ GUARDED_BY(network_state_lock_);
   // Duplicate the pacer paused state to avoid grabbing a lock when
   // pausing the pacer. This can be removed when we move this class
   // over to the task queue.
   bool pacer_paused_;
   rtc::CriticalSection bwe_lock_;
   int min_bitrate_bps_ GUARDED_BY(bwe_lock_);
   std::unique_ptr<DelayBasedBwe> delay_based_bwe_ GUARDED_BY(bwe_lock_);
-  const bool in_cwnd_experiment_;
+  bool in_cwnd_experiment_;
+  int64_t accepted_queue_ms_;
   bool was_in_alr_;
 
   rtc::RaceChecker worker_race_;
 
   RTC_DISALLOW_IMPLICIT_CONSTRUCTORS(SendSideCongestionController);
 };
 
 }  // namespace webrtc
 
 #endif  // WEBRTC_MODULES_CONGESTION_CONTROLLER_INCLUDE_SEND_SIDE_CONGESTION_CONTROLLER_H_