Move usage of QualityScaler to ViEEncoder.

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

Index: webrtc/modules/video_coding/codecs/vp8/vp8_impl.h
diff --git a/webrtc/modules/video_coding/codecs/vp8/vp8_impl.h b/webrtc/modules/video_coding/codecs/vp8/vp8_impl.h
index 00a711554d5a5e367f7ebeccf8065d81731c2658..37c8fe685b7433192092a3fc391716b9cf65193c 100644
--- a/webrtc/modules/video_coding/codecs/vp8/vp8_impl.h
+++ b/webrtc/modules/video_coding/codecs/vp8/vp8_impl.h
@@ -59,6 +59,8 @@ class VP8EncoderImpl : public VP8Encoder {
 
   void OnDroppedFrame() override;
 
+  QualityScaler::Settings GetQPThresholds() const override;
+
   const char* ImplementationName() const override;
 
  private:
@@ -116,8 +118,6 @@ class VP8EncoderImpl : public VP8Encoder {
   std::vector<vpx_codec_ctx_t> encoders_;
   std::vector<vpx_codec_enc_cfg_t> configurations_;
   std::vector<vpx_rational_t> downsampling_factors_;
-  QualityScaler quality_scaler_;
-  bool quality_scaler_enabled_;
 };  // end of VP8EncoderImpl class
 
 class VP8DecoderImpl : public VP8Decoder {