Don't count frames passed to VP8 BWE disabled streams as being encoded

This excludes these frames from being counted as dropped by encoder.
Also fix bitrate projected distribution for vp9 svc for outliers
detection.

Bug: webrtc:8497
Change-Id: Id37487456170c61e2323a660668f0c319ea5831d
Reviewed-on: https://webrtc-review.googlesource.com/21223
Commit-Queue: Ilya Nikolaevskiy <ilnik@webrtc.org>
Reviewed-by: Erik Språng <sprang@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#20632}
diff --git a/modules/video_coding/generic_encoder.h b/modules/video_coding/generic_encoder.h
index 878588d..dc94e4a 100644
--- a/modules/video_coding/generic_encoder.h
+++ b/modules/video_coding/generic_encoder.h
@@ -135,7 +135,8 @@
   const bool internal_source_;
   rtc::CriticalSection params_lock_;
   EncoderParameters encoder_params_ RTC_GUARDED_BY(params_lock_);
-  size_t streams_or_svc_num_;
+  size_t streams_or_svc_num_ RTC_GUARDED_BY(race_checker_);
+  VideoCodecType codec_type_ RTC_GUARDED_BY(race_checker_);
 };
 
 }  // namespace webrtc