Push back on the video encoder to avoid building queues in the pacer.

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 136 matching lines @@
   bool pacer_paused_;
   rtc::CriticalSection bwe_lock_;
   int min_bitrate_bps_ RTC_GUARDED_BY(bwe_lock_);
   std::unique_ptr<DelayBasedBwe> delay_based_bwe_ RTC_GUARDED_BY(bwe_lock_);
   bool in_cwnd_experiment_;
   int64_t accepted_queue_ms_;
   bool was_in_alr_;
 
   rtc::RaceChecker worker_race_;
 
+  bool pacer_pushback_experiment_ = false;
+  float encoding_rate_ = 1.0;
+
   RTC_DISALLOW_IMPLICIT_CONSTRUCTORS(SendSideCongestionController);
 };
 
 }  // namespace webrtc
 
 #endif  // MODULES_CONGESTION_CONTROLLER_INCLUDE_SEND_SIDE_CONGESTION_CONTROLLER_H_