Add codec name to CodecSpecificInfo and get the codec name stats from there instead.

webrtc/modules/video_coding/codecs/vp9/vp9_impl.cc

Index: webrtc/modules/video_coding/codecs/vp9/vp9_impl.cc
diff --git a/webrtc/modules/video_coding/codecs/vp9/vp9_impl.cc b/webrtc/modules/video_coding/codecs/vp9/vp9_impl.cc
index 884196ad7e1a5b0ae4edf77bba831dfb91acec92..f6eaf0257b63be86937c75b0edbc087c26ca9f4d 100644
--- a/webrtc/modules/video_coding/codecs/vp9/vp9_impl.cc
+++ b/webrtc/modules/video_coding/codecs/vp9/vp9_impl.cc
@@ -560,6 +560,7 @@ void VP9EncoderImpl::PopulateCodecSpecific(CodecSpecificInfo* codec_specific,
                                            uint32_t timestamp) {
   assert(codec_specific != NULL);
   codec_specific->codecType = kVideoCodecVP9;
+  codec_specific->codec_name = ImplementationName();
   CodecSpecificInfoVP9* vp9_info = &(codec_specific->codecSpecific.VP9);
   // TODO(asapersson): Set correct value.
   vp9_info->inter_pic_predicted =