Replace NULL with nullptr in all C++ files.

webrtc/p2p/base/stunport.cc

Index: webrtc/p2p/base/stunport.cc
diff --git a/webrtc/p2p/base/stunport.cc b/webrtc/p2p/base/stunport.cc
index be844d54dc4bd8d0f72759471da831e4737206ef..9444b8af16e932d381c6b6ba06add68f3d94c217 100644
--- a/webrtc/p2p/base/stunport.cc
+++ b/webrtc/p2p/base/stunport.cc
@@ -202,7 +202,7 @@ UDPPort::UDPPort(rtc::Thread* thread,
            username,
            password),
       requests_(thread),
-      socket_(NULL),
+      socket_(nullptr),
       error_(0),
       ready_(false),
       stun_keepalive_delay_(KEEPALIVE_DELAY),
@@ -213,7 +213,7 @@ UDPPort::UDPPort(rtc::Thread* thread,
 bool UDPPort::Init() {
   stun_keepalive_lifetime_ = GetStunKeepaliveLifetime();
   if (!SharedSocket()) {
-    RTC_DCHECK(socket_ == NULL);
+    RTC_DCHECK(socket_ == nullptr);
     socket_ = socket_factory()->CreateUdpSocket(
         rtc::SocketAddress(ip(), 0), min_port(), max_port());
     if (!socket_) {
@@ -255,16 +255,16 @@ void UDPPort::MaybePrepareStunCandidate() {
 Connection* UDPPort::CreateConnection(const Candidate& address,
                                       CandidateOrigin origin) {
   if (!SupportsProtocol(address.protocol())) {
-    return NULL;
+    return nullptr;
   }
 
   if (!IsCompatibleAddress(address.address())) {
-    return NULL;
+    return nullptr;
   }
 
   if (SharedSocket() && Candidates()[0].type() != LOCAL_PORT_TYPE) {
     RTC_NOTREACHED();
-    return NULL;
+    return nullptr;
   }
 
   Connection* conn = new ProxyConnection(this, 0, address);
@@ -376,7 +376,7 @@ void UDPPort::ResolveStunAddress(const rtc::SocketAddress& stun_addr) {
 
 void UDPPort::OnResolveResult(const rtc::SocketAddress& input,
                               int error) {
-  RTC_DCHECK(resolver_.get() != NULL);
+  RTC_DCHECK(resolver_.get() != nullptr);
 
   rtc::SocketAddress resolved;
   if (error != 0 ||