Add QP sum stats for received streams.

webrtc/modules/video_coding/generic_decoder.h

Index: webrtc/modules/video_coding/generic_decoder.h
diff --git a/webrtc/modules/video_coding/generic_decoder.h b/webrtc/modules/video_coding/generic_decoder.h
index 2d0007be81136102221d39ff2a5ff32eebb4ca8a..1cb30237ac6d629c94993efa526284da7296a72e 100644
--- a/webrtc/modules/video_coding/generic_decoder.h
+++ b/webrtc/modules/video_coding/generic_decoder.h
@@ -37,11 +37,13 @@ class VCMDecodedFrameCallback : public DecodedImageCallback {
     void SetUserReceiveCallback(VCMReceiveCallback* receiveCallback);
     VCMReceiveCallback* UserReceiveCallback();
 
-    virtual int32_t Decoded(VideoFrame& decodedImage);  // NOLINT
-    virtual int32_t Decoded(VideoFrame& decodedImage,   // NOLINT
-                            int64_t decode_time_ms);
-    virtual int32_t ReceivedDecodedReferenceFrame(const uint64_t pictureId);
-    virtual int32_t ReceivedDecodedFrame(const uint64_t pictureId);
+    int32_t Decoded(VideoFrame& decodedImage) override;
+    int32_t Decoded(VideoFrame& decodedImage, int64_t decode_time_ms) override;
+    int32_t Decoded(VideoFrame& decodedImage,
+                    rtc::Optional<int32_t> decode_time_ms,
+                    rtc::Optional<uint8_t> qp) override;
+    int32_t ReceivedDecodedReferenceFrame(const uint64_t pictureId) override;
+    int32_t ReceivedDecodedFrame(const uint64_t pictureId) override;
 
     uint64_t LastReceivedPictureID() const;
     void OnDecoderImplementationName(const char* implementation_name);