Replace NULL with nullptr in all C++ files.

webrtc/p2p/base/asyncstuntcpsocket_unittest.cc

Index: webrtc/p2p/base/asyncstuntcpsocket_unittest.cc
diff --git a/webrtc/p2p/base/asyncstuntcpsocket_unittest.cc b/webrtc/p2p/base/asyncstuntcpsocket_unittest.cc
index 5929d1f84dae322d3026e7400c381ee1a0f1b79f..ba08dd9a46610f6c1341977c29b7209b6dd07ab7 100644
--- a/webrtc/p2p/base/asyncstuntcpsocket_unittest.cc
+++ b/webrtc/p2p/base/asyncstuntcpsocket_unittest.cc
@@ -69,9 +69,7 @@ class AsyncStunTCPSocketTest : public testing::Test,
                                public sigslot::has_slots<> {
  protected:
   AsyncStunTCPSocketTest()
-      : vss_(new rtc::VirtualSocketServer(NULL)),
-        ss_scope_(vss_.get()) {
-  }
+      : vss_(new rtc::VirtualSocketServer(nullptr)), ss_scope_(vss_.get()) {}
 
   virtual void SetUp() {
     CreateSockets();
@@ -89,7 +87,7 @@ class AsyncStunTCPSocketTest : public testing::Test,
         kClientAddr.family(), SOCK_STREAM);
     send_socket_.reset(AsyncStunTCPSocket::Create(
         client, kClientAddr, recv_socket_->GetLocalAddress()));
-    ASSERT_TRUE(send_socket_.get() != NULL);
+    ASSERT_TRUE(send_socket_.get() != nullptr);
     vss_->ProcessMessagesUntilIdle();
   }