RTCMediaStreamTrackStats.framesSent collected by RTCStatsCollector.

BUG=webrtc:6757, chromium:659137, chromium:627816

Review-Url: https://codereview.webrtc.org/2606033002
Cr-Commit-Position: refs/heads/master@{#16188}
diff --git a/webrtc/api/rtcstats_integrationtest.cc b/webrtc/api/rtcstats_integrationtest.cc
index f89207a..903c8c8 100644
--- a/webrtc/api/rtcstats_integrationtest.cc
+++ b/webrtc/api/rtcstats_integrationtest.cc
@@ -438,11 +438,13 @@
       verifier.TestMemberIsNonNegative<uint32_t>(
           media_stream_track.frame_height);
       verifier.TestMemberIsUndefined(media_stream_track.frames_per_second);
-      verifier.TestMemberIsUndefined(media_stream_track.frames_sent);
       if (*media_stream_track.remote_source) {
+        verifier.TestMemberIsUndefined(media_stream_track.frames_sent);
         verifier.TestMemberIsNonNegative<uint32_t>(
             media_stream_track.frames_received);
       } else {
+        verifier.TestMemberIsNonNegative<uint32_t>(
+            media_stream_track.frames_sent);
         verifier.TestMemberIsUndefined(media_stream_track.frames_received);
       }
       verifier.TestMemberIsUndefined(media_stream_track.frames_decoded);