Add default downscale threshold to QualityScaler.

webrtc/modules/video_coding/codecs/vp8/vp8_impl.cc

 /*
  *  Copyright (c) 2012 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.
  */
 
@@ skipping 585 matching lines @@
       SetStreamState(send_stream, stream_idx);
       configurations_[i].rc_target_bitrate = stream_bitrate;
       temporal_layers_[stream_idx]->ConfigureBitrates(stream_bitrate,
                                                       inst->maxBitrate,
                                                       inst->maxFramerate,
                                                       &configurations_[i]);
     }
   }
 
   rps_.Init();
-  quality_scaler_.Init(codec_.qpMax / kDefaultLowQpDenominator);
+  quality_scaler_.Init(codec_.qpMax / QualityScaler::kDefaultLowQpDenominator);
   quality_scaler_.ReportFramerate(codec_.maxFramerate);
 
   return InitAndSetControlSettings();
 }
 
 int VP8EncoderImpl::SetCpuSpeed(int width, int height) {
 #if defined(WEBRTC_ARCH_ARM) || defined(WEBRTC_ARCH_ARM64)
   // On mobile platform, always set to -12 to leverage between cpu usage
   // and video quality.
   return -12;
@@ skipping 778 matching lines @@
     return -1;
   }
   if (vpx_codec_control(copy->decoder_, VP8_SET_REFERENCE, ref_frame_)
       != VPX_CODEC_OK) {
     return -1;
   }
   return 0;
 }
 
 }  // namespace webrtc