Replace NULL with nullptr in all C++ files.

webrtc/modules/video_coding/codecs/vp8/simulcast_encoder_adapter.cc

Index: webrtc/modules/video_coding/codecs/vp8/simulcast_encoder_adapter.cc
diff --git a/webrtc/modules/video_coding/codecs/vp8/simulcast_encoder_adapter.cc b/webrtc/modules/video_coding/codecs/vp8/simulcast_encoder_adapter.cc
index ae1151162ac19376c1e6a2620b6d2b082df050f0..e543bb912bfea86e669fdf33d78e093981ccb7ad 100644
--- a/webrtc/modules/video_coding/codecs/vp8/simulcast_encoder_adapter.cc
+++ b/webrtc/modules/video_coding/codecs/vp8/simulcast_encoder_adapter.cc
@@ -62,7 +62,7 @@ bool ValidSimulcastResolutions(const webrtc::VideoCodec& codec,
 }
 
 int VerifyCodec(const webrtc::VideoCodec* inst) {
-  if (inst == NULL) {
+  if (inst == nullptr) {
     return WEBRTC_VIDEO_CODEC_ERR_PARAMETER;
   }
   if (inst->maxFramerate < 1) {
@@ -250,7 +250,7 @@ int SimulcastEncoderAdapter::Encode(
   if (!Initialized()) {
     return WEBRTC_VIDEO_CODEC_UNINITIALIZED;
   }
-  if (encoded_complete_callback_ == NULL) {
+  if (encoded_complete_callback_ == nullptr) {
     return WEBRTC_VIDEO_CODEC_UNINITIALIZED;
   }