MediaCodecVideoEncoder: Add QP stats to Encoded callback for VP9 and turn on quality scaling.

webrtc/modules/video_coding/utility/quality_scaler.cc

Index: webrtc/modules/video_coding/utility/quality_scaler.cc
diff --git a/webrtc/modules/video_coding/utility/quality_scaler.cc b/webrtc/modules/video_coding/utility/quality_scaler.cc
index f1623cb6e974b66c4857570bf23ef3a4df3782f2..3709ee3bf51f4b34bb6695d7765f970c243b14fd 100644
--- a/webrtc/modules/video_coding/utility/quality_scaler.cc
+++ b/webrtc/modules/video_coding/utility/quality_scaler.cc
@@ -39,6 +39,11 @@ static const int kHighH264QpThreshold = 37;
 // bitstream range of [0, 127] and not the user-level range of [0,63].
 static const int kLowVp8QpThreshold = 29;
 static const int kHighVp8QpThreshold = 95;
+// QP is obtained from VP9-bitstream for HW, so the QP corresponds to the
+// bitstream range of [0, 255] and not the user-level range of [0,63].
+// Current VP9 settings are mapped from VP8 thresholds above.
+static const int kLowVp9QpThreshold = 96;
+static const int kHighVp9QpThreshold = 208;
 static const int kMinFramesNeededToScale = 2 * 30;
 
 static VideoEncoder::QpThresholds CodecTypeToDefaultThresholds(
@@ -54,6 +59,10 @@ static VideoEncoder::QpThresholds CodecTypeToDefaultThresholds(
       low = kLowVp8QpThreshold;
       high = kHighVp8QpThreshold;
       break;
+    case kVideoCodecVP9:
+      low = kLowVp9QpThreshold;
+      high = kHighVp9QpThreshold;
+      break;
     default:
       RTC_NOTREACHED() << "Invalid codec type for QualityScaler.";
   }