Add default downscale threshold to QualityScaler.

webrtc/modules/video_coding/utility/include/quality_scaler.h

 /*
  *  Copyright (c) 2014 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
 #ifndef WEBRTC_MODULES_VIDEO_CODING_UTILITY_QUALITY_SCALER_H_
 #define WEBRTC_MODULES_VIDEO_CODING_UTILITY_QUALITY_SCALER_H_
 
 #include "webrtc/common_video/libyuv/include/scaler.h"
 #include "webrtc/modules/video_coding/utility/include/moving_average.h"
 
 namespace webrtc {
-const int kDefaultLowQpDenominator = 3;
 class QualityScaler {
  public:
+  static const int kDefaultLowQpDenominator;
+  static const int kDefaultMinDownscaleDimension;
   struct Resolution {
     int width;
     int height;
   };
 
   QualityScaler();
   void Init(int low_qp_threshold);
   void SetMinResolution(int min_width, int min_height);
   void ReportFramerate(int framerate);
   void ReportQP(int qp);
@@ skipping 15 matching lines @@
   MovingAverage<int> average_qp_;
 
   int downscale_shift_;
   int min_width_;
   int min_height_;
 };
 
 }  // namespace webrtc
 
 #endif  // WEBRTC_MODULES_VIDEO_CODING_UTILITY_QUALITY_SCALER_H_