Reland of Make QualityScaler more responsive to downgrades.

webrtc/modules/video_coding/utility/quality_scaler.h

Index: webrtc/modules/video_coding/utility/quality_scaler.h
diff --git a/webrtc/modules/video_coding/utility/quality_scaler.h b/webrtc/modules/video_coding/utility/quality_scaler.h
index ebceb06893401eca490e40758f2355e444fbf475..34dda0e9f37a44fb8f6cfdf03b0837ee13c90386 100644
--- a/webrtc/modules/video_coding/utility/quality_scaler.h
+++ b/webrtc/modules/video_coding/utility/quality_scaler.h
@@ -30,7 +30,8 @@
             bool use_framerate_reduction,
             int initial_bitrate_kbps,
             int width,
-            int height);
+            int height,
+            int fps);
   void SetMinResolution(int min_width, int min_height);
   void ReportFramerate(int framerate);
   void ReportQP(int qp);
@@ -46,17 +47,22 @@
   void AdjustScale(bool up);
   void UpdateTargetResolution(int frame_width, int frame_height);
   void ClearSamples();
+  void UpdateSampleCounts();
 
   Scaler scaler_;
   VideoFrame scaled_frame_;
 
-  size_t num_samples_;
+  size_t num_samples_downscale_;
+  size_t num_samples_upscale_;
+  int measure_seconds_upscale_;
+  MovingAverage<int> average_qp_upscale_;
+  MovingAverage<int> average_qp_downscale_;
+
   int framerate_;
   int target_framerate_;
   int low_qp_threshold_;
   int high_qp_threshold_;
   MovingAverage<int> framedrop_percent_;
-  MovingAverage<int> average_qp_;
   Resolution res_;
 
   int downscale_shift_;