Replace NULL with nullptr in all C++ files.

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

Index: webrtc/modules/video_coding/codecs/vp8/realtime_temporal_layers.cc
diff --git a/webrtc/modules/video_coding/codecs/vp8/realtime_temporal_layers.cc b/webrtc/modules/video_coding/codecs/vp8/realtime_temporal_layers.cc
index f842fb4213379e95980417a5a13b3e015407dcb4..dcc1015e6e46a4f2485aeb29854ee195ba260264 100644
--- a/webrtc/modules/video_coding/codecs/vp8/realtime_temporal_layers.cc
+++ b/webrtc/modules/video_coding/codecs/vp8/realtime_temporal_layers.cc
@@ -219,14 +219,14 @@ class RealTimeTemporalLayers : public TemporalLayers {
   }
 
   int CurrentEncodeFlags() const {
-    assert(encode_flags_length_ > 0 && encode_flags_ != NULL);
+    assert(encode_flags_length_ > 0 && encode_flags_ != nullptr);
     int index = frame_counter_ % encode_flags_length_;
     assert(index >= 0 && index < encode_flags_length_);
     return encode_flags_[index];
   }
 
   int CurrentLayerId() const override {
-    assert(layer_ids_length_ > 0 && layer_ids_ != NULL);
+    assert(layer_ids_length_ > 0 && layer_ids_ != nullptr);
     int index = frame_counter_ % layer_ids_length_;
     assert(index >= 0 && index < layer_ids_length_);
     return layer_ids_[index];