Replace NULL with nullptr in all C++ files.

webrtc/modules/rtp_rtcp/source/rtp_format_vp8_test_helper.cc

 /*
  *  Copyright (c) 2012 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.
  */
 
 
 #include "webrtc/modules/rtp_rtcp/source/rtp_format_vp8_test_helper.h"
 
 #include "webrtc/test/gtest.h"
 
 namespace webrtc {
 
 namespace test {
 
 constexpr RtpPacketToSend::ExtensionManager* kNoExtensions = nullptr;
 
 RtpFormatVp8TestHelper::RtpFormatVp8TestHelper(const RTPVideoHeaderVP8* hdr)
     : packet_(kNoExtensions),
-      payload_data_(NULL),
-      data_ptr_(NULL),
-      fragmentation_(NULL),
+      payload_data_(nullptr),
+      data_ptr_(nullptr),
+      fragmentation_(nullptr),
       hdr_info_(hdr),
       payload_start_(0),
       payload_size_(0),
       sloppy_partitioning_(false),
       inited_(false) {}
 
 RtpFormatVp8TestHelper::~RtpFormatVp8TestHelper() {
   delete fragmentation_;
   delete [] payload_data_;
 }
@@ skipping 204 matching lines @@
                                          bool frag_start) {
   EXPECT_EQ(expect_bytes, packet_.payload_size());
   CheckHeader(frag_start);
   CheckPayload();
   CheckLast(last);
 }
 
 }  // namespace test
 
 }  // namespace webrtc