Check that stats_proxy_ is non-NULL before use.

webrtc/video/vie_encoder.cc

Index: webrtc/video/vie_encoder.cc
diff --git a/webrtc/video/vie_encoder.cc b/webrtc/video/vie_encoder.cc
index 95a6f5a18c9f54a8139292fcfd05167cfdc8af3c..a3fd98dd6fe5b1c74ebd00de4c55388597949afd 100644
--- a/webrtc/video/vie_encoder.cc
+++ b/webrtc/video/vie_encoder.cc
@@ -463,8 +463,9 @@ void ViEEncoder::ReconfigureEncoder() {
 
 void ViEEncoder::OnFrame(const VideoFrame& video_frame) {
   RTC_DCHECK_RUNS_SERIALIZED(&incoming_frame_race_checker_);
-  stats_proxy_->OnIncomingFrame(video_frame.width(), video_frame.height());
-
+  if (stats_proxy_) {
+    stats_proxy_->OnIncomingFrame(video_frame.width(), video_frame.height());
+  }
   VideoFrame incoming_frame = video_frame;
 
   // Local time in webrtc time base.