Replace NULL with nullptr in all C++ files.

webrtc/pc/peerconnection.cc

Index: webrtc/pc/peerconnection.cc
diff --git a/webrtc/pc/peerconnection.cc b/webrtc/pc/peerconnection.cc
index 96e2b339a49d25faa32e449b2944c362b27c946a..aa6efe4aeacad3c719cb6e02f9a31ceb48556194 100644
--- a/webrtc/pc/peerconnection.cc
+++ b/webrtc/pc/peerconnection.cc
@@ -689,8 +689,8 @@ RTCErrorType ParseIceServers(
 
 PeerConnection::PeerConnection(PeerConnectionFactory* factory)
     : factory_(factory),
-      observer_(NULL),
-      uma_observer_(NULL),
+      observer_(nullptr),
+      uma_observer_(nullptr),
       signaling_state_(kStable),
       ice_connection_state_(kIceConnectionNew),
       ice_gathering_state_(kIceGatheringNew),
@@ -953,7 +953,7 @@ rtc::scoped_refptr<DtmfSenderInterface> PeerConnection::CreateDtmfSender(
     return nullptr;
   }
   if (!track) {
-    LOG(LS_ERROR) << "CreateDtmfSender - track is NULL.";
+    LOG(LS_ERROR) << "CreateDtmfSender - track is null.";
     return nullptr;
   }
   auto it = FindSenderForTrack(track);
@@ -1015,7 +1015,7 @@ bool PeerConnection::GetStats(StatsObserver* observer,
   TRACE_EVENT0("webrtc", "PeerConnection::GetStats");
   RTC_DCHECK(signaling_thread()->IsCurrent());
   if (!observer) {
-    LOG(LS_ERROR) << "GetStats - observer is NULL.";
+    LOG(LS_ERROR) << "GetStats - observer is null.";
     return false;
   }
 
@@ -1058,7 +1058,7 @@ PeerConnection::CreateDataChannel(
   TRACE_EVENT0("webrtc", "PeerConnection::CreateDataChannel");
 #ifdef HAVE_QUIC
   if (session_->data_channel_type() == cricket::DCT_QUIC) {
-    // TODO(zhihuang): Handle case when config is NULL.
+    // TODO(zhihuang): Handle case when config is null.
     if (!config) {
       LOG(LS_ERROR) << "Missing config for QUIC data channel.";
       return nullptr;
@@ -1098,7 +1098,7 @@ void PeerConnection::CreateOffer(CreateSessionDescriptionObserver* observer,
                                  const MediaConstraintsInterface* constraints) {
   TRACE_EVENT0("webrtc", "PeerConnection::CreateOffer");
   if (!observer) {
-    LOG(LS_ERROR) << "CreateOffer - observer is NULL.";
+    LOG(LS_ERROR) << "CreateOffer - observer is null.";
     return;
   }
   RTCOfferAnswerOptions options;
@@ -1150,7 +1150,7 @@ void PeerConnection::CreateOffer(CreateSessionDescriptionObserver* observer,
                                  const RTCOfferAnswerOptions& options) {
   TRACE_EVENT0("webrtc", "PeerConnection::CreateOffer");
   if (!observer) {
-    LOG(LS_ERROR) << "CreateOffer - observer is NULL.";
+    LOG(LS_ERROR) << "CreateOffer - observer is null.";
     return;
   }
 
@@ -1170,7 +1170,7 @@ void PeerConnection::CreateAnswer(
     const MediaConstraintsInterface* constraints) {
   TRACE_EVENT0("webrtc", "PeerConnection::CreateAnswer");
   if (!observer) {
-    LOG(LS_ERROR) << "CreateAnswer - observer is NULL.";
+    LOG(LS_ERROR) << "CreateAnswer - observer is null.";
     return;
   }
 
@@ -1189,7 +1189,7 @@ void PeerConnection::CreateAnswer(CreateSessionDescriptionObserver* observer,
                                   const RTCOfferAnswerOptions& options) {
   TRACE_EVENT0("webrtc", "PeerConnection::CreateAnswer");
   if (!observer) {
-    LOG(LS_ERROR) << "CreateAnswer - observer is NULL.";
+    LOG(LS_ERROR) << "CreateAnswer - observer is null.";
     return;
   }
 
@@ -1212,11 +1212,11 @@ void PeerConnection::SetLocalDescription(
     return;
   }
   if (!observer) {
-    LOG(LS_ERROR) << "SetLocalDescription - observer is NULL.";
+    LOG(LS_ERROR) << "SetLocalDescription - observer is null.";
     return;
   }
   if (!desc) {
-    PostSetSessionDescriptionFailure(observer, "SessionDescription is NULL.");
+    PostSetSessionDescriptionFailure(observer, "SessionDescription is null.");
     return;
   }
   // Update stats here so that we have the most recent stats for tracks and
@@ -1294,11 +1294,11 @@ void PeerConnection::SetRemoteDescription(
     return;
   }
   if (!observer) {
-    LOG(LS_ERROR) << "SetRemoteDescription - observer is NULL.";
+    LOG(LS_ERROR) << "SetRemoteDescription - observer is null.";
     return;
   }
   if (!desc) {
-    PostSetSessionDescriptionFailure(observer, "SessionDescription is NULL.");
+    PostSetSessionDescriptionFailure(observer, "SessionDescription is null.");
     return;
   }
   // Update stats here so that we have the most recent stats for tracks and