Rename RTCOutboundRTPStreamStats *_rtt members to *_round_trip_time.

The spec renamed these recently:
https://w3c.github.io/webrtc-stats/#since-21-sep-2016*

BUG=chromium:627816

Review-Url: https://codereview.webrtc.org/2576383002
Cr-Commit-Position: refs/heads/master@{#15630}
diff --git a/webrtc/api/rtcstats_integrationtest.cc b/webrtc/api/rtcstats_integrationtest.cc
index 9600f2a..db54b17 100644
--- a/webrtc/api/rtcstats_integrationtest.cc
+++ b/webrtc/api/rtcstats_integrationtest.cc
@@ -334,8 +334,8 @@
     verifier.TestMemberIsUndefined(candidate_pair.readable);
     verifier.TestMemberIsDefined(candidate_pair.bytes_sent);
     verifier.TestMemberIsDefined(candidate_pair.bytes_received);
-    verifier.TestMemberIsUndefined(candidate_pair.total_rtt);
-    verifier.TestMemberIsDefined(candidate_pair.current_rtt);
+    verifier.TestMemberIsUndefined(candidate_pair.total_round_trip_time);
+    verifier.TestMemberIsDefined(candidate_pair.current_round_trip_time);
     verifier.TestMemberIsUndefined(candidate_pair.available_outgoing_bitrate);
     verifier.TestMemberIsUndefined(candidate_pair.available_incoming_bitrate);
     verifier.TestMemberIsDefined(candidate_pair.requests_received);
diff --git a/webrtc/api/rtcstatscollector.cc b/webrtc/api/rtcstatscollector.cc
index f5d3e5f..a6d691c 100644
--- a/webrtc/api/rtcstatscollector.cc
+++ b/webrtc/api/rtcstatscollector.cc
@@ -640,7 +640,7 @@
         // TODO(hbos): The |info.rtt| measurement is smoothed. It shouldn't be
         // smoothed according to the spec. crbug.com/633550. See
         // https://w3c.github.io/webrtc-stats/#dom-rtcicecandidatepairstats-currentrtt
-        candidate_pair_stats->current_rtt =
+        candidate_pair_stats->current_round_trip_time =
             static_cast<double>(info.rtt) / rtc::kNumMillisecsPerSec;
         candidate_pair_stats->requests_received =
             static_cast<uint64_t>(info.recv_ping_requests);
diff --git a/webrtc/api/rtcstatscollector_unittest.cc b/webrtc/api/rtcstatscollector_unittest.cc
index 0e1fef0..697cc30 100644
--- a/webrtc/api/rtcstatscollector_unittest.cc
+++ b/webrtc/api/rtcstatscollector_unittest.cc
@@ -1043,7 +1043,7 @@
   expected_pair.writable = true;
   expected_pair.bytes_sent = 42;
   expected_pair.bytes_received = 1234;
-  expected_pair.current_rtt = 1.337;
+  expected_pair.current_round_trip_time = 1.337;
   expected_pair.requests_received = 2020;
   expected_pair.requests_sent = 2000;
   expected_pair.responses_received = 4321;
diff --git a/webrtc/api/stats/rtcstats_objects.h b/webrtc/api/stats/rtcstats_objects.h
index 04797e9..429f93b 100644
--- a/webrtc/api/stats/rtcstats_objects.h
+++ b/webrtc/api/stats/rtcstats_objects.h
@@ -134,10 +134,10 @@
   RTCStatsMember<uint64_t> bytes_sent;
   RTCStatsMember<uint64_t> bytes_received;
   // TODO(hbos): Not collected by |RTCStatsCollector|. crbug.com/633550
-  RTCStatsMember<double> total_rtt;
+  RTCStatsMember<double> total_round_trip_time;
   // TODO(hbos): Collected by |RTCStatsCollector| but different than the spec.
   // crbug.com/633550
-  RTCStatsMember<double> current_rtt;
+  RTCStatsMember<double> current_round_trip_time;
   // TODO(hbos): Not collected by |RTCStatsCollector|. crbug.com/633550
   RTCStatsMember<double> available_outgoing_bitrate;
   // TODO(hbos): Not collected by |RTCStatsCollector|. crbug.com/633550
diff --git a/webrtc/stats/rtcstats_objects.cc b/webrtc/stats/rtcstats_objects.cc
index 46cf0c3..73d070e 100644
--- a/webrtc/stats/rtcstats_objects.cc
+++ b/webrtc/stats/rtcstats_objects.cc
@@ -155,8 +155,8 @@
     &readable,
     &bytes_sent,
     &bytes_received,
-    &total_rtt,
-    &current_rtt,
+    &total_round_trip_time,
+    &current_round_trip_time,
     &available_outgoing_bitrate,
     &available_incoming_bitrate,
     &requests_received,
@@ -188,8 +188,8 @@
       readable("readable"),
       bytes_sent("bytesSent"),
       bytes_received("bytesReceived"),
-      total_rtt("totalRtt"),
-      current_rtt("currentRtt"),
+      total_round_trip_time("totalRoundTripTime"),
+      current_round_trip_time("currentRoundTripTime"),
       available_outgoing_bitrate("availableOutgoingBitrate"),
       available_incoming_bitrate("availableIncomingBitrate"),
       requests_received("requestsReceived"),
@@ -217,8 +217,8 @@
       readable(other.readable),
       bytes_sent(other.bytes_sent),
       bytes_received(other.bytes_received),
-      total_rtt(other.total_rtt),
-      current_rtt(other.current_rtt),
+      total_round_trip_time(other.total_round_trip_time),
+      current_round_trip_time(other.current_round_trip_time),
       available_outgoing_bitrate(other.available_outgoing_bitrate),
       available_incoming_bitrate(other.available_incoming_bitrate),
       requests_received(other.requests_received),