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 8bfa72fe1ef47e83ec38961ef5f01e4dbb7b0edf..ad8e0440fd4e39b7397dd5ad3a3800d4ab3e5d71 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 {
 
@@ -68,7 +70,6 @@ class VideoEncoder {
     kVp9,
     kUnsupportedCodec,
   };
-
   static VideoEncoder* Create(EncoderType codec_type);
   // Returns true if this type of encoder can be created using
   // VideoEncoder::Create.
@@ -150,6 +151,12 @@ 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; }
@@ -180,6 +187,7 @@ 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();