Fix stats for encoder target bitrate when target rate is zero.

webrtc/modules/video_coding/generic_encoder.h

Index: webrtc/modules/video_coding/generic_encoder.h
diff --git a/webrtc/modules/video_coding/generic_encoder.h b/webrtc/modules/video_coding/generic_encoder.h
index 0493d319aa93e99a69331c7afbc7bd8cd69d0957..9f73f36e5d6e5e153ff13c5db2a365bfdc28ae07 100644
--- a/webrtc/modules/video_coding/generic_encoder.h
+++ b/webrtc/modules/video_coding/generic_encoder.h
@@ -59,7 +59,6 @@ class VCMGenericEncoder {
 
  public:
   VCMGenericEncoder(VideoEncoder* encoder,
-                    VideoEncoderRateObserver* rate_observer,
                     VCMEncodedFrameCallback* encoded_frame_callback,
                     bool internal_source);
   ~VCMGenericEncoder();
@@ -86,7 +85,6 @@ class VCMGenericEncoder {
   rtc::RaceChecker race_checker_;
 
   VideoEncoder* const encoder_ GUARDED_BY(race_checker_);
-  VideoEncoderRateObserver* const rate_observer_;
   VCMEncodedFrameCallback* const vcm_encoded_frame_callback_;
   const bool internal_source_;
   rtc::CriticalSection params_lock_;