Move RTCOutboundRTPStreamStats.roundTripTime to inbound, don't collect.

The value is being moved:
https://github.com/w3c/webrtc-stats/pull/167

Stop collecting this value. Our previous value was incorrect, our RTT
value was a smoothed value based on STUN pings but the spec says it
should be based on RTCP timestamps in RTCP Receiver Report (RR) on
inbound streams with isRemote=true (not supported).

Updated some bug references.

BUG=webrtc:7065, webrtc:7066

Review-Url: https://codereview.webrtc.org/2722633005
Cr-Commit-Position: refs/heads/master@{#16931}
diff --git a/webrtc/pc/rtcstats_integrationtest.cc b/webrtc/pc/rtcstats_integrationtest.cc
index 1176b54..922e07c 100644
--- a/webrtc/pc/rtcstats_integrationtest.cc
+++ b/webrtc/pc/rtcstats_integrationtest.cc
@@ -553,6 +553,7 @@
       verifier.TestMemberIsNonNegative<double>(inbound_stream.jitter);
     }
     verifier.TestMemberIsNonNegative<double>(inbound_stream.fraction_lost);
+    verifier.TestMemberIsUndefined(inbound_stream.round_trip_time);
     verifier.TestMemberIsUndefined(inbound_stream.packets_discarded);
     verifier.TestMemberIsUndefined(inbound_stream.packets_repaired);
     verifier.TestMemberIsUndefined(inbound_stream.burst_packets_lost);
@@ -585,8 +586,6 @@
     verifier.TestMemberIsNonNegative<uint32_t>(outbound_stream.packets_sent);
     verifier.TestMemberIsNonNegative<uint64_t>(outbound_stream.bytes_sent);
     verifier.TestMemberIsUndefined(outbound_stream.target_bitrate);
-    // TODO(hbos): Defined in video but not audio case. Why? crbug.com/669877
-    verifier.MarkMemberTested(outbound_stream.round_trip_time, true);
     if (outbound_stream.media_type.is_defined() &&
         *outbound_stream.media_type == "video") {
       verifier.TestMemberIsDefined(outbound_stream.frames_encoded);