Replace NULL with nullptr in all C++ files.

webrtc/voice_engine/test/auto_test/fixtures/before_streaming_fixture.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.
  */
 
 #include "webrtc/test/testsupport/fileutils.h"
 #include "webrtc/voice_engine/test/auto_test/fixtures/before_streaming_fixture.h"
 
 BeforeStreamingFixture::BeforeStreamingFixture()
-    : channel_(voe_base_->CreateChannel()),
-      transport_(NULL) {
+    : channel_(voe_base_->CreateChannel()), transport_(nullptr) {
   EXPECT_GE(channel_, 0);
 
   fake_microphone_input_file_ =
       webrtc::test::ResourcePath("voice_engine/audio_long16", "pcm");
 
   SetUpLocalPlayback();
   RestartFakeMicrophone();
 }
 
 BeforeStreamingFixture::~BeforeStreamingFixture() {
@@ skipping 42 matching lines @@
   codec.plfreq = 8000;
   codec.pltype = 0;
   codec.rate = 64000;
 #if defined(_MSC_VER) && defined(_WIN32)
   _snprintf(codec.plname, RTP_PAYLOAD_NAME_SIZE - 1, "PCMU");
 #else
   snprintf(codec.plname, RTP_PAYLOAD_NAME_SIZE, "PCMU");
 #endif
   voe_codec_->SetSendCodec(channel_, codec);
 }