Reland of Add QP sum stats for received streams.

webrtc/video_receive_stream.h

Index: webrtc/video_receive_stream.h
diff --git a/webrtc/video_receive_stream.h b/webrtc/video_receive_stream.h
index 374f3508a14b36d2222be1ba0b2afddc0ffe500a..12629d06378085b2a0bbee04d4877284390593e5 100644
--- a/webrtc/video_receive_stream.h
+++ b/webrtc/video_receive_stream.h
@@ -70,6 +70,7 @@
     int min_playout_delay_ms = 0;
     int render_delay_ms = 10;
     uint32_t frames_decoded = 0;
+    rtc::Optional<uint64_t> qp_sum;
 
     int current_payload_type = -1;