Replace NULL with nullptr in all C++ files.

webrtc/test/rtp_file_writer.cc

 /*
  *  Copyright (c) 2014 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 10 matching lines @@
 namespace test {
 
 static const uint16_t kPacketHeaderSize = 8;
 static const char kFirstLine[] = "#!rtpplay1.0 0.0.0.0/0\n";
 
 // Write RTP packets to file in rtpdump format, as documented at:
 // http://www.cs.columbia.edu/irt/software/rtptools/
 class RtpDumpWriter : public RtpFileWriter {
  public:
   explicit RtpDumpWriter(FILE* file) : file_(file) {
-    RTC_CHECK(file_ != NULL);
+    RTC_CHECK(file_ != nullptr);
     Init();
   }
   virtual ~RtpDumpWriter() {
-    if (file_ != NULL) {
+    if (file_ != nullptr) {
       fclose(file_);
-      file_ = NULL;
+      file_ = nullptr;
     }
   }
 
   bool WritePacket(const RtpPacket* packet) override {
     uint16_t len = static_cast<uint16_t>(packet->length + kPacketHeaderSize);
     uint16_t plen = static_cast<uint16_t>(packet->original_length);
     uint32_t offset = packet->time_ms;
     RTC_CHECK(WriteUint16(len));
     RTC_CHECK(WriteUint16(plen));
     RTC_CHECK(WriteUint32(offset));
@@ skipping 37 matching lines @@
   }
 
   FILE* file_;
 
   RTC_DISALLOW_COPY_AND_ASSIGN(RtpDumpWriter);
 };
 
 RtpFileWriter* RtpFileWriter::Create(FileFormat format,
                                      const std::string& filename) {
   FILE* file = fopen(filename.c_str(), "wb");
-  if (file == NULL) {
+  if (file == nullptr) {
     printf("ERROR: Can't open file: %s\n", filename.c_str());
-    return NULL;
+    return nullptr;
   }
   switch (format) {
     case kRtpDump:
       return new RtpDumpWriter(file);
   }
   fclose(file);
-  return NULL;
+  return nullptr;
 }
 
 }  // namespace test
 }  // namespace webrtc