Replace NULL with nullptr in all C++ files.

webrtc/media/sctp/sctptransport.cc

Index: webrtc/media/sctp/sctptransport.cc
diff --git a/webrtc/media/sctp/sctptransport.cc b/webrtc/media/sctp/sctptransport.cc
index ae69628a98b8a0031f1fe0d57ac5b5b92bf42bdf..6bf5d03c85df7944a22f2f2654cc23fc97154117 100644
--- a/webrtc/media/sctp/sctptransport.cc
+++ b/webrtc/media/sctp/sctptransport.cc
@@ -161,7 +161,7 @@ PayloadProtocolIdentifier GetPpid(cricket::DataMessageType type) {
 
 bool GetDataMediaType(PayloadProtocolIdentifier ppid,
                       cricket::DataMessageType* dest) {
-  RTC_DCHECK(dest != NULL);
+  RTC_DCHECK(dest != nullptr);
   switch (ppid) {
     case PPID_BINARY_PARTIAL:
     case PPID_BINARY_LAST:
@@ -194,7 +194,7 @@ void VerboseLogPacket(const void* data, size_t length, int direction) {
     // a non-const "void*" as first parameter when dumping the packet, so we
     // need to cast the const away here to avoid a compiler error.
     if ((dump_buf = usrsctp_dumppacket(const_cast<void*>(data), length,
-                                       direction)) != NULL) {
+                                       direction)) != nullptr) {
       LOG(LS_VERBOSE) << dump_buf;
       usrsctp_freedumpbuffer(dump_buf);
     }
@@ -543,8 +543,8 @@ bool SctpTransport::SendData(const SendDataParams& params,
 
   // We don't fragment.
   send_res = usrsctp_sendv(
-      sock_, payload.data(), static_cast<size_t>(payload.size()), NULL, 0, &spa,
-      rtc::checked_cast<socklen_t>(sizeof(spa)), SCTP_SENDV_SPA, 0);
+      sock_, payload.data(), static_cast<size_t>(payload.size()), nullptr, 0,
+      &spa, rtc::checked_cast<socklen_t>(sizeof(spa)), SCTP_SENDV_SPA, 0);
   if (send_res < 0) {
     if (errno == SCTP_EWOULDBLOCK) {
       *result = SDR_BLOCK;
@@ -901,8 +901,8 @@ void SctpTransport::OnInboundPacketFromSctpToChannel(
                   << " sid=" << params.sid
                   << " notification: " << (flags & MSG_NOTIFICATION)
                   << " length=" << buffer.size();
-  // Sending a packet with data == NULL (no data) is SCTPs "close the
-  // connection" message. This sets sock_ = NULL;
+  // Sending a packet with data == null (no data) is SCTPs "close the
+  // connection" message. This sets sock_ = null;
   if (!buffer.size() || !buffer.data()) {
     LOG(LS_INFO) << debug_name_ << "->OnInboundPacketFromSctpToChannel(...): "
                                    "No data, closing.";