Add QP stats for sent 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 fb828ef6c65ab965eaf120f038949666dc1d8b56..051d32f5e44fce4be8287d881eee40dd70e563dc 100644
--- a/talk/media/base/mediachannel.h
+++ b/talk/media/base/mediachannel.h
@@ -772,7 +772,8 @@ struct VideoSenderInfo : public MediaSenderInfo {
         adapt_reason(0),
         adapt_changes(0),
         avg_encode_ms(0),
-        encode_usage_percent(0) {
+        encode_usage_percent(0),
+        qp(-1) {
   }
 
   std::vector<SsrcGroup> ssrc_groups;
@@ -795,6 +796,7 @@ struct VideoSenderInfo : public MediaSenderInfo {
   VariableInfo<int> adapt_frame_drops;
   VariableInfo<int> effects_frame_drops;
   VariableInfo<double> capturer_frame_time;
+  int qp;  // Average codec quantizer value.
 };
 
 struct VideoReceiverInfo : public MediaReceiverInfo {