Move usage of QualityScaler to ViEEncoder.

webrtc/video_encoder.h

Index: webrtc/video_encoder.h
diff --git a/webrtc/video_encoder.h b/webrtc/video_encoder.h
index 9bfec55eb7ddc48659b0063ebc13fa3c4f49c7bb..1ac6bd2892541f0f3cb27709260e9645f39f36dd 100644
--- a/webrtc/video_encoder.h
+++ b/webrtc/video_encoder.h
@@ -18,6 +18,8 @@
 #include "webrtc/common_types.h"
 #include "webrtc/typedefs.h"
 #include "webrtc/video_frame.h"
+#include "webrtc/base/optional.h"
+#include "webrtc/modules/video_coding/utility/quality_scaler.h"
 
 namespace webrtc {
 
@@ -81,7 +83,6 @@ class VideoEncoder {
     kVp9,
     kUnsupportedCodec,
   };
-
   static VideoEncoder* Create(EncoderType codec_type);
 
   static VideoCodecVP8 GetDefaultVp8Settings();
@@ -159,6 +160,12 @@ class VideoEncoder {
   // Return value                : WEBRTC_VIDEO_CODEC_OK if OK, < 0 otherwise.
   virtual int32_t SetRates(uint32_t bitrate, uint32_t framerate) = 0;
 
+  // Any encoder implementation wishing to use the WebRTC provided
+  // quality scaler must implement this method.
+  virtual QualityScaler::Settings GetQPThresholds() const {
+    return QualityScaler::Settings(false);
+  }
+
   virtual int32_t SetPeriodicKeyFrames(bool enable) { return -1; }
   virtual void OnDroppedFrame() {}
   virtual bool SupportsNativeHandle() const { return false; }
@@ -189,6 +196,7 @@ class VideoEncoderSoftwareFallbackWrapper : public VideoEncoder {
   int32_t SetRates(uint32_t bitrate, uint32_t framerate) override;
   void OnDroppedFrame() override;
   bool SupportsNativeHandle() const override;
+  QualityScaler::Settings GetQPThresholds() const override;
 
  private:
   bool InitFallbackEncoder();