Add probing to recover faster from large bitrate drops.

webrtc/modules/congestion_controller/probe_controller.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.
  */
 
@@ skipping 20 matching lines @@
   void SetBitrates(int64_t min_bitrate_bps,
                    int64_t start_bitrate_bps,
                    int64_t max_bitrate_bps);
 
   void OnNetworkStateChanged(NetworkState state);
 
   void SetEstimatedBitrate(int64_t bitrate_bps);
 
   void EnablePeriodicAlrProbing(bool enable);
 
+  void SetAlrEndedTimeMs(int64_t alr_end_time);
+
+  void RequestProbe(uint32_t bitrate_bps);
+
   // Resets the ProbeController to a state equivalent to as if it was just
   // created EXCEPT for |enable_periodic_alr_probing_|.
   void Reset();
 
   void Process();
 
  private:
   enum class State {
     // Initial state where no probing has been triggered yet.
     kInit,
@@ skipping 11 matching lines @@
   rtc::CriticalSection critsect_;
   PacedSender* const pacer_;
   const Clock* const clock_;
   NetworkState network_state_ GUARDED_BY(critsect_);
   State state_ GUARDED_BY(critsect_);
   int64_t min_bitrate_to_probe_further_bps_ GUARDED_BY(critsect_);
   int64_t time_last_probing_initiated_ms_ GUARDED_BY(critsect_);
   int64_t estimated_bitrate_bps_ GUARDED_BY(critsect_);
   int64_t start_bitrate_bps_ GUARDED_BY(critsect_);
   int64_t max_bitrate_bps_ GUARDED_BY(critsect_);
-  int64_t last_alr_probing_time_ GUARDED_BY(critsect_);
+  int64_t last_bwe_drop_probing_time_ms_ GUARDED_BY(critsect_);
+  rtc::Optional<int64_t> alr_end_time_ms_ GUARDED_BY(critsect_);
   bool enable_periodic_alr_probing_ GUARDED_BY(critsect_);
+  bool in_rapid_recovery_experiment_ GUARDED_BY(critsect_);
 
   // For WebRTC.BWE.MidCallProbing.* metric.
   bool mid_call_probing_waiting_for_result_ GUARDED_BY(&critsect_);
   int64_t mid_call_probing_bitrate_bps_ GUARDED_BY(&critsect_);
   int64_t mid_call_probing_succcess_threshold_ GUARDED_BY(&critsect_);
 
   RTC_DISALLOW_IMPLICIT_CONSTRUCTORS(ProbeController);
 };
 
 }  // namespace webrtc
 
 #endif  // WEBRTC_MODULES_CONGESTION_CONTROLLER_PROBE_CONTROLLER_H_