RTCTransportStats.dtlsState replaces .activeConnection

In accordance with recent spec change:
https://github.com/w3c/webrtc-stats/pull/122

BUG=chromium:653873, chromium:627816

Review-Url: https://codereview.webrtc.org/2625993002
Cr-Commit-Position: refs/heads/master@{#16098}
diff --git a/webrtc/api/rtcstats_integrationtest.cc b/webrtc/api/rtcstats_integrationtest.cc
index 69dc834..7a67038 100644
--- a/webrtc/api/rtcstats_integrationtest.cc
+++ b/webrtc/api/rtcstats_integrationtest.cc
@@ -572,7 +572,7 @@
     verifier.TestMemberIsNonNegative<uint64_t>(transport.bytes_received);
     verifier.TestMemberIsOptionalIDReference(
         transport.rtcp_transport_stats_id, RTCTransportStats::kType);
-    verifier.TestMemberIsDefined(transport.active_connection);
+    verifier.TestMemberIsDefined(transport.dtls_state);
     verifier.TestMemberIsIDReference(
         transport.selected_candidate_pair_id, RTCIceCandidatePairStats::kType);
     verifier.TestMemberIsIDReference(