Add QP stats for received video streams to StatsReport.

talk/media/base/mediachannel.h

Index: talk/media/base/mediachannel.h
diff --git a/talk/media/base/mediachannel.h b/talk/media/base/mediachannel.h
index 14660847fa2114b0138a4cfcdf33440d58f86f26..2e36ccfe9a199064260faf2be9645cc270c1a08c 100644
--- a/talk/media/base/mediachannel.h
+++ b/talk/media/base/mediachannel.h
@@ -861,7 +861,8 @@ struct VideoReceiverInfo : public MediaReceiverInfo {
         render_delay_ms(0),
         target_delay_ms(0),
         current_delay_ms(0),
-        capture_start_ntp_time_ms(-1) {
+        capture_start_ntp_time_ms(-1),
+        qp(-1) {
   }
 
   std::vector<SsrcGroup> ssrc_groups;
@@ -901,6 +902,8 @@ struct VideoReceiverInfo : public MediaReceiverInfo {
 
   // Estimated capture start time in NTP time in ms.
   int64_t capture_start_ntp_time_ms;
+  // Average codec quantizer value.
+  int qp;
 };
 
 struct DataSenderInfo : public MediaSenderInfo {