Replace NULL with nullptr in all C++ files.

webrtc/media/engine/fakewebrtccall.cc

Index: webrtc/media/engine/fakewebrtccall.cc
diff --git a/webrtc/media/engine/fakewebrtccall.cc b/webrtc/media/engine/fakewebrtccall.cc
index 0cdc4d486315accaca5f61d26f7bd361e9f1f17f..00f2d05d925a2ae92b935c43a9bfadaad2ea18b5 100644
--- a/webrtc/media/engine/fakewebrtccall.cc
+++ b/webrtc/media/engine/fakewebrtccall.cc
@@ -109,7 +109,7 @@ FakeVideoSendStream::FakeVideoSendStream(
       resolution_scaling_enabled_(false),
       source_(nullptr),
       num_swapped_frames_(0) {
-  RTC_DCHECK(config.encoder_settings.encoder != NULL);
+  RTC_DCHECK(config.encoder_settings.encoder != nullptr);
   ReconfigureVideoEncoder(std::move(encoder_config));
 }
 
@@ -212,7 +212,7 @@ void FakeVideoSendStream::ReconfigureVideoEncoder(
   }
   video_streams_ = config.video_stream_factory->CreateEncoderStreams(
       width, height, config);
-  if (config.encoder_specific_settings != NULL) {
+  if (config.encoder_specific_settings != nullptr) {
     if (config_.encoder_settings.payload_name == "VP8") {
       config.encoder_specific_settings->FillVideoCodecVp8(&vpx_settings_.vp8);
       if (!video_streams_.empty()) {
@@ -230,7 +230,7 @@ void FakeVideoSendStream::ReconfigureVideoEncoder(
                     << config_.encoder_settings.payload_name;
     }
   }
-  codec_settings_set_ = config.encoder_specific_settings != NULL;
+  codec_settings_set_ = config.encoder_specific_settings != nullptr;
   encoder_config_ = std::move(config);
   ++num_encoder_reconfigurations_;
 }