Perform probing on network route change.

webrtc/modules/congestion_controller/congestion_controller.cc

 /*
  *  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 214 matching lines @@
   bitrate_controller_->ResetBitrates(bitrate_bps, min_bitrate_bps,
                                      max_bitrate_bps);
   min_bitrate_bps_ = min_bitrate_bps;
   max_bitrate_bps_ = max_bitrate_bps;
   // TODO(honghaiz): Recreate this object once the remote bitrate estimator is
   // no longer exposed outside CongestionController.
   remote_bitrate_estimator_.SetMinBitrate(min_bitrate_bps);
 
   transport_feedback_adapter_.InitBwe();
   transport_feedback_adapter_.SetStartBitrate(bitrate_bps);
   transport_feedback_adapter_.SetMinBitrate(min_bitrate_bps);

[stefan-webrtc, 2017/02/22 14:38:00]

Reading this code makes me think... What happens if we get acks from packets
sent on the previous transport after this? Should we reset the SendTimeHistory
here as well, or at least remove instances which are from the old transport
pair?

[philipel, 2017/02/23 11:57:01]

SendTimeHistory is now also cleared when ResetBweAndBitrates is called.

-  // TODO(holmer): Trigger a new probe once mid-call probing is implemented.
+
+  probe_controller_.reset(new ProbeController(pacer_.get(), clock_));
+  probe_controller_->SetBitrates(min_bitrate_bps, bitrate_bps, max_bitrate_bps);
+
   MaybeTriggerOnNetworkChanged();
 }
 
 BitrateController* CongestionController::GetBitrateController() const {
   return bitrate_controller_.get();
 }
 
 RemoteBitrateEstimator* CongestionController::GetRemoteBitrateEstimator(
     bool send_side_bwe) {
   if (send_side_bwe) {
@@ skipping 123 matching lines @@
 bool CongestionController::IsSendQueueFull() const {
   return pacer_->ExpectedQueueTimeMs() > PacedSender::kMaxQueueLengthMs;
 }
 
 bool CongestionController::IsNetworkDown() const {
   rtc::CritScope cs(&critsect_);
   return network_state_ == kNetworkDown;
 }
 
 }  // namespace webrtc