Add PeerConnection IsClosed check.

webrtc/api/peerconnection.cc

Index: webrtc/api/peerconnection.cc
diff --git a/webrtc/api/peerconnection.cc b/webrtc/api/peerconnection.cc
index 506a21582f7ae0ce6f4dffa34497ac72b4dc14ee..890007652cafc53bf3ed3de38c98158eae82315d 100644
--- a/webrtc/api/peerconnection.cc
+++ b/webrtc/api/peerconnection.cc
@@ -758,6 +758,9 @@ bool PeerConnection::RemoveTrack(RtpSenderInterface* sender) {
 rtc::scoped_refptr<DtmfSenderInterface> PeerConnection::CreateDtmfSender(
     AudioTrackInterface* track) {
   TRACE_EVENT0("webrtc", "PeerConnection::CreateDtmfSender");
+  if (IsClosed()) {
+    return nullptr;
+  }
   if (!track) {
     LOG(LS_ERROR) << "CreateDtmfSender - track is NULL.";
     return NULL;
@@ -780,6 +783,9 @@ rtc::scoped_refptr<RtpSenderInterface> PeerConnection::CreateSender(
     const std::string& kind,
     const std::string& stream_id) {
   TRACE_EVENT0("webrtc", "PeerConnection::CreateSender");
+  if (IsClosed()) {
+    return nullptr;
+  }
   rtc::scoped_refptr<RtpSenderInterface> new_sender;
   if (kind == MediaStreamTrackInterface::kAudioKind) {
     new_sender = RtpSenderProxy::Create(
@@ -982,6 +988,9 @@ void PeerConnection::SetLocalDescription(
     SetSessionDescriptionObserver* observer,
     SessionDescriptionInterface* desc) {
   TRACE_EVENT0("webrtc", "PeerConnection::SetLocalDescription");
+  if (IsClosed()) {
+    return;
+  }
   if (!VERIFY(observer != nullptr)) {
     LOG(LS_ERROR) << "SetLocalDescription - observer is NULL.";
     return;
@@ -1060,6 +1069,9 @@ void PeerConnection::SetRemoteDescription(
     SetSessionDescriptionObserver* observer,
     SessionDescriptionInterface* desc) {
   TRACE_EVENT0("webrtc", "PeerConnection::SetRemoteDescription");
+  if (IsClosed()) {
+    return;
+  }
   if (!VERIFY(observer != nullptr)) {
     LOG(LS_ERROR) << "SetRemoteDescription - observer is NULL.";
     return;
@@ -1175,6 +1187,9 @@ bool PeerConnection::SetConfiguration(const RTCConfiguration& config) {
 bool PeerConnection::AddIceCandidate(
     const IceCandidateInterface* ice_candidate) {
   TRACE_EVENT0("webrtc", "PeerConnection::AddIceCandidate");
+  if (IsClosed()) {
+    return false;
+  }
   return session_->ProcessIceMessage(ice_candidate);
 }
 
@@ -1360,17 +1375,26 @@ void PeerConnection::OnIceGatheringChange(
 
 void PeerConnection::OnIceCandidate(const IceCandidateInterface* candidate) {
   RTC_DCHECK(signaling_thread()->IsCurrent());
+  if (IsClosed()) {
+    return;
+  }
   observer_->OnIceCandidate(candidate);
 }
 
 void PeerConnection::OnIceCandidatesRemoved(
     const std::vector<cricket::Candidate>& candidates) {
   RTC_DCHECK(signaling_thread()->IsCurrent());
+  if (IsClosed()) {
+    return;
+  }
   observer_->OnIceCandidatesRemoved(candidates);
 }
 
 void PeerConnection::OnIceConnectionReceivingChange(bool receiving) {
   RTC_DCHECK(signaling_thread()->IsCurrent());
+  if (IsClosed()) {
+    return;
+  }
   observer_->OnIceConnectionReceivingChange(receiving);
 }
 
@@ -1390,6 +1414,9 @@ void PeerConnection::ChangeSignalingState(
 
 void PeerConnection::OnAudioTrackAdded(AudioTrackInterface* track,
                                        MediaStreamInterface* stream) {
+  if (IsClosed()) {
+    return;
+  }
   auto sender = FindSenderForTrack(track);
   if (sender != senders_.end()) {
     // We already have a sender for this track, so just change the stream_id
@@ -1420,6 +1447,9 @@ void PeerConnection::OnAudioTrackAdded(AudioTrackInterface* track,
 // indefinitely, when we have unified plan SDP.
 void PeerConnection::OnAudioTrackRemoved(AudioTrackInterface* track,
                                          MediaStreamInterface* stream) {
+  if (IsClosed()) {
+    return;
+  }
   auto sender = FindSenderForTrack(track);
   if (sender == senders_.end()) {
     LOG(LS_WARNING) << "RtpSender for track with id " << track->id()
@@ -1432,6 +1462,9 @@ void PeerConnection::OnAudioTrackRemoved(AudioTrackInterface* track,
 
 void PeerConnection::OnVideoTrackAdded(VideoTrackInterface* track,
                                        MediaStreamInterface* stream) {
+  if (IsClosed()) {
+    return;
+  }
   auto sender = FindSenderForTrack(track);
   if (sender != senders_.end()) {
     // We already have a sender for this track, so just change the stream_id
@@ -1454,6 +1487,9 @@ void PeerConnection::OnVideoTrackAdded(VideoTrackInterface* track,
 
 void PeerConnection::OnVideoTrackRemoved(VideoTrackInterface* track,
                                          MediaStreamInterface* stream) {
+  if (IsClosed()) {
+    return;
+  }
   auto sender = FindSenderForTrack(track);
   if (sender == senders_.end()) {
     LOG(LS_WARNING) << "RtpSender for track with id " << track->id()