Add QP stats for sent video streams to StatsReport.

webrtc/video/send_statistics_proxy.h

Index: webrtc/video/send_statistics_proxy.h
diff --git a/webrtc/video/send_statistics_proxy.h b/webrtc/video/send_statistics_proxy.h
index 7209094fe68a70342de60992ea2acc6e4528ef47..53923e58c5d8684989f5144f0db94c7ee9657a38 100644
--- a/webrtc/video/send_statistics_proxy.h
+++ b/webrtc/video/send_statistics_proxy.h
@@ -116,6 +116,13 @@ class SendStatisticsProxy : public CpuOveruseMetricsObserver,
     int64_t resolution_update_ms;
     int64_t bitrate_update_ms;
   };
+  struct QpCounters {
+    SampleCounter vp8;
+  };
+  struct QpFilter {
+    QpFilter() : qp(0.97f) {}  // Weight factor.
+    rtc::ExpFilter qp;
+  };
   void PurgeOldStats() EXCLUSIVE_LOCKS_REQUIRED(crit_);
   VideoSendStream::StreamStats* GetStatsEntry(uint32_t ssrc)
       EXCLUSIVE_LOCKS_REQUIRED(crit_);
@@ -144,6 +151,10 @@ class SendStatisticsProxy : public CpuOveruseMetricsObserver,
   SampleCounter bw_resolutions_disabled_counter_ GUARDED_BY(crit_);
   SampleCounter delay_counter_ GUARDED_BY(crit_);
   SampleCounter max_delay_counter_ GUARDED_BY(crit_);
+  // QP counters mapped by SSRC.
+  std::map<uint32_t, QpCounters> qp_counters_ GUARDED_BY(crit_);
+  // QP filter mapped by SSRC.
+  std::map<uint32_t, QpFilter> qp_filters_ GUARDED_BY(crit_);
 };
 
 }  // namespace webrtc