Add QP sum stats for received streams.

webrtc/pc/statscollector_unittest.cc

Index: webrtc/pc/statscollector_unittest.cc
diff --git a/webrtc/pc/statscollector_unittest.cc b/webrtc/pc/statscollector_unittest.cc
index ef218c00c665af7ee36655d7597db1ed1b0c302c..455d136b511c7070fc9f9e2477f2c9d10fdb1bf2 100644
--- a/webrtc/pc/statscollector_unittest.cc
+++ b/webrtc/pc/statscollector_unittest.cc
@@ -2019,6 +2019,7 @@ TEST_F(StatsCollectorTest, VerifyVideoReceiveSsrcStats) {
   // Construct a stats value to read.
   video_receiver_info.add_ssrc(1234);
   video_receiver_info.frames_decoded = 10;
+  video_receiver_info.qp_sum = rtc::Optional<uint64_t>(11);
   stats_read.receivers.push_back(video_receiver_info);
 
   EXPECT_CALL(session_, video_channel()).WillRepeatedly(Return(&video_channel));
@@ -2030,6 +2031,8 @@ TEST_F(StatsCollectorTest, VerifyVideoReceiveSsrcStats) {
   EXPECT_EQ(rtc::ToString(video_receiver_info.frames_decoded),
             ExtractSsrcStatsValue(reports,
                                   StatsReport::kStatsValueNameFramesDecoded));
+  EXPECT_EQ(rtc::ToString(*video_receiver_info.qp_sum),
+            ExtractSsrcStatsValue(reports, StatsReport::kStatsValueNameQpSum));
 }
 
 }  // namespace webrtc