Replace NULL with nullptr in all C++ files.

webrtc/voice_engine/test/channel_transport/udp_socket_wrapper_unittest.cc

Index: webrtc/voice_engine/test/channel_transport/udp_socket_wrapper_unittest.cc
diff --git a/webrtc/voice_engine/test/channel_transport/udp_socket_wrapper_unittest.cc b/webrtc/voice_engine/test/channel_transport/udp_socket_wrapper_unittest.cc
index befd61108dd14d712c79f702bcc59b787709200b..7c53a31bff5e1549037ebc79b1e89ea3114f97a5 100644
--- a/webrtc/voice_engine/test/channel_transport/udp_socket_wrapper_unittest.cc
+++ b/webrtc/voice_engine/test/channel_transport/udp_socket_wrapper_unittest.cc
@@ -53,12 +53,11 @@ TEST(UdpSocketWrapper, CreateSocket) {
   uint8_t threads = 1;
   UdpSocketManager* mgr = UdpSocketManager::Create(id, threads);
   UdpSocketWrapper* socket =
-      UdpSocketWrapper::CreateSocket(id,
-                                     mgr,
-                                     NULL,  // CallbackObj
-                                     NULL,  // IncomingSocketCallback
-                                     false,  // ipV6Enable
-                                     false);  // disableGQOS
+      UdpSocketWrapper::CreateSocket(id, mgr,
+                                     nullptr,  // CallbackObj
+                                     nullptr,  // IncomingSocketCallback
+                                     false,    // ipV6Enable
+                                     false);   // disableGQOS
   socket->CloseBlocking();
   UdpSocketManager::Return();
 }