Fixing a segfault that can occur when changing the track of an RtpSender.

webrtc/api/rtpsender.cc

 /*
  *  Copyright 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 104 matching lines @@
     track_->RemoveSink(sink_adapter_.get());
     track_->UnregisterObserver(this);
   }
 
   if (can_send_track() && stats_) {
     stats_->RemoveLocalAudioTrack(track_.get(), ssrc_);
   }
 
   // Attach to new track.
   bool prev_can_send_track = can_send_track();
+  // Keep a reference to the old track to keep it alive until we call
+  // SetAudioSend.
+  rtc::scoped_refptr<AudioTrackInterface> old_track = track_;
   track_ = audio_track;
   if (track_) {
     cached_track_enabled_ = track_->enabled();
     track_->RegisterObserver(this);
     track_->AddSink(sink_adapter_.get());
   }
 
   // Update audio provider.
   if (can_send_track()) {
     SetAudioSend();
@@ skipping 134 matching lines @@
   }
   VideoTrackInterface* video_track = static_cast<VideoTrackInterface*>(track);
 
   // Detach from old track.
   if (track_) {
     track_->UnregisterObserver(this);
   }
 
   // Attach to new track.
   bool prev_can_send_track = can_send_track();
+  // Keep a reference to the old track to keep it alive until we call
+  // SetSource.
+  rtc::scoped_refptr<VideoTrackInterface> old_track = track_;
   track_ = video_track;
   if (track_) {
     cached_track_enabled_ = track_->enabled();
     track_->RegisterObserver(this);
   }
 
   // Update video provider.
   if (can_send_track()) {
     // TODO(deadbeef): If SetTrack is called with a disabled track, and the
     // previous track was enabled, this could cause a frame from the new track
@@ skipping 57 matching lines @@
 RtpParameters VideoRtpSender::GetParameters() const {
   return provider_->GetVideoRtpParameters(ssrc_);
 }
 
 bool VideoRtpSender::SetParameters(const RtpParameters& parameters) {
   TRACE_EVENT0("webrtc", "VideoRtpSender::SetParameters");
   return provider_->SetVideoRtpParameters(ssrc_, parameters);
 }
 
 }  // namespace webrtc