Replace NULL with nullptr or null in webrtc/base/.

webrtc/base/testclient_unittest.cc

 /*
  *  Copyright 2006 The WebRTC Project Authors. All rights reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 21 matching lines @@
 }
 
 void TestTcpInternal(const SocketAddress& loopback) {
   Thread *main = Thread::Current();
   TestEchoServer server(main, loopback);
 
   AsyncSocket* socket = main->socketserver()
       ->CreateAsyncSocket(loopback.family(), SOCK_STREAM);
   AsyncTCPSocket* tcp_socket = AsyncTCPSocket::Create(
       socket, loopback, server.address());
-  ASSERT_TRUE(tcp_socket != NULL);
+  ASSERT_TRUE(tcp_socket != nullptr);
 
   TestClient client(tcp_socket);
   SocketAddress addr = client.address(), from;
   EXPECT_TRUE(client.CheckConnected());
   EXPECT_EQ(3, client.Send("foo", 3));
   EXPECT_TRUE(client.CheckNextPacket("foo", 3, &from));
   EXPECT_EQ(from, server.address());
   EXPECT_TRUE(client.CheckNoPacket());
 }
 
@@ skipping 25 matching lines @@
 #else
 #define MAYBE_TestTcpIPv6 TestTcpIPv6
 #endif
 TEST(TestClientTest, MAYBE_TestTcpIPv6) {
   if (HasIPv6Enabled()) {
     TestTcpInternal(SocketAddress("::1", 0));
   } else {
     LOG(LS_INFO) << "Skipping IPv6 test.";
   }
 }