QUIC - (no behavior change) s/NULL/nullptr/g in .../quic/...

net/quic/congestion_control/send_algorithm_interface.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "net/quic/congestion_control/send_algorithm_interface.h"
 
 #include "net/quic/congestion_control/tcp_cubic_sender.h"
 #include "net/quic/quic_protocol.h"
 
 namespace net {
@@ skipping 10 matching lines @@
     case kCubic:
       return new TcpCubicSender(clock, rtt_stats,
                                 false /* don't use Reno */,
                                 kMaxTcpCongestionWindow, stats);
     case kReno:
       return new TcpCubicSender(clock, rtt_stats,
                                 true /* use Reno */,
                                 kMaxTcpCongestionWindow, stats);
     case kBBR:
       LOG(DFATAL) << "BbrTcpSender is not supported.";
-      return NULL;
+      return nullptr;
   }
-  return NULL;
+  return nullptr;
 }
 
 }  // namespace net