RTCMediaStreamTrackStats.framesDropped collected by RTCStatsCollector.

webrtc/pc/rtcstats_integrationtest.cc

Index: webrtc/pc/rtcstats_integrationtest.cc
diff --git a/webrtc/pc/rtcstats_integrationtest.cc b/webrtc/pc/rtcstats_integrationtest.cc
index 6bba2cbce177f8f5985a57ef0125003f037d8ac7..076527677fafb75acf87e2693b77d40792585e12 100644
--- a/webrtc/pc/rtcstats_integrationtest.cc
+++ b/webrtc/pc/rtcstats_integrationtest.cc
@@ -444,13 +444,15 @@ class RTCStatsReportVerifier {
             media_stream_track.frames_received);
         verifier.TestMemberIsNonNegative<uint32_t>(
             media_stream_track.frames_decoded);
+        verifier.TestMemberIsNonNegative<uint32_t>(
+            media_stream_track.frames_dropped);
       } else {
         verifier.TestMemberIsNonNegative<uint32_t>(
             media_stream_track.frames_sent);
         verifier.TestMemberIsUndefined(media_stream_track.frames_received);
         verifier.TestMemberIsUndefined(media_stream_track.frames_decoded);
+        verifier.TestMemberIsUndefined(media_stream_track.frames_dropped);
       }
-      verifier.TestMemberIsUndefined(media_stream_track.frames_dropped);
       verifier.TestMemberIsUndefined(media_stream_track.frames_corrupted);
       verifier.TestMemberIsUndefined(media_stream_track.partial_frames_lost);
       verifier.TestMemberIsUndefined(media_stream_track.full_frames_lost);