Replace NULL with nullptr in all C++ files.

webrtc/modules/audio_coding/neteq/neteq_impl.cc

Index: webrtc/modules/audio_coding/neteq/neteq_impl.cc
diff --git a/webrtc/modules/audio_coding/neteq/neteq_impl.cc b/webrtc/modules/audio_coding/neteq/neteq_impl.cc
index 09a32965ed70116d3c3066f528701a720f85f85c..68ab4814b1366689ad18fafb0e1874878eb5ce12 100644
--- a/webrtc/modules/audio_coding/neteq/neteq_impl.cc
+++ b/webrtc/modules/audio_coding/neteq/neteq_impl.cc
@@ -248,7 +248,7 @@ int NetEqImpl::RegisterExternalDecoder(AudioDecoder* decoder,
                   << static_cast<int>(rtp_payload_type) << " "
                   << static_cast<int>(codec);
   if (!decoder) {
-    LOG(LS_ERROR) << "Cannot register external decoder with NULL pointer";
+    LOG(LS_ERROR) << "Cannot register external decoder with null pointer";
     assert(false);
     return kFail;
   }
@@ -2064,7 +2064,7 @@ void NetEqImpl::SetSampleRateAndChannels(int fs_hz, size_t channels) {
     cng_decoder->Reset();
 
   // Reinit post-decode VAD with new sample rate.
-  assert(vad_.get());  // Cannot be NULL here.
+  assert(vad_.get());  // Cannot be nullptr here.
   vad_->Init();
 
   // Delete algorithm buffer and create a new one.