Reland of "Change TWCC send interval to reduce overhead on low BW situations."

webrtc/modules/remote_bitrate_estimator/remote_estimator_proxy.h

 /*
  *  Copyright (c) 2015 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 29 matching lines @@
   void IncomingPacket(int64_t arrival_time_ms,
                       size_t payload_size,
                       const RTPHeader& header) override;
   void RemoveStream(uint32_t ssrc) override {}
   bool LatestEstimate(std::vector<unsigned int>* ssrcs,
                       unsigned int* bitrate_bps) const override;
   void OnRttUpdate(int64_t avg_rtt_ms, int64_t max_rtt_ms) override {}
   void SetMinBitrate(int min_bitrate_bps) override {}
   int64_t TimeUntilNextProcess() override;
   void Process() override;
+  void OnBitrateChanged(int bitrate);
 
-  static const int kDefaultProcessIntervalMs;
+  static const int kMinSendIntervalMs;
+  static const int kMaxSendIntervalMs;
+  static const int kDefaultSendIntervalMs;
   static const int kBackWindowMs;
 
  private:
   void OnPacketArrival(uint16_t sequence_number, int64_t arrival_time)
       EXCLUSIVE_LOCKS_REQUIRED(&lock_);
   bool BuildFeedbackPacket(rtcp::TransportFeedback* feedback_packet);
 
   Clock* const clock_;
   PacketRouter* const packet_router_;
   int64_t last_process_time_ms_;
 
   rtc::CriticalSection lock_;
 
   uint32_t media_ssrc_ GUARDED_BY(&lock_);
   uint8_t feedback_sequence_ GUARDED_BY(&lock_);
   SequenceNumberUnwrapper unwrapper_ GUARDED_BY(&lock_);
   int64_t window_start_seq_ GUARDED_BY(&lock_);
   // Map unwrapped seq -> time.
   std::map<int64_t, int64_t> packet_arrival_times_ GUARDED_BY(&lock_);
+  int64_t send_interval_ms_ GUARDED_BY(&lock_);
 };
 
 }  // namespace webrtc
 
 #endif  //  WEBRTC_MODULES_REMOTE_BITRATE_ESTIMATOR_REMOTE_ESTIMATOR_PROXY_H_