RTCStatsIntegrationTest: TestMemberIsIDReference on all defined IDs.

This makes sure that the referenced stats dictionaries exist.

BUG=chromium:627816

Review-Url: https://codereview.webrtc.org/2577033002
Cr-Original-Commit-Position: refs/heads/master@{#15628}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: 7bf536976366443ea59153ff3d22da0ec32badc1
diff --git a/api/rtcstats_integrationtest.cc b/api/rtcstats_integrationtest.cc
index 0f60377..9600f2a 100644
--- a/api/rtcstats_integrationtest.cc
+++ b/api/rtcstats_integrationtest.cc
@@ -450,7 +450,7 @@
     verifier->TestMemberIsUndefined(stream.media_track_id);
     verifier->TestMemberIsIDReference(
         stream.transport_id, RTCTransportStats::kType);
-    verifier->TestMemberIsDefined(stream.codec_id);
+    verifier->TestMemberIsIDReference(stream.codec_id, RTCCodecStats::kType);
     if (stream.media_type.is_defined() && *stream.media_type == "video") {
       verifier->TestMemberIsDefined(stream.fir_count);
       verifier->TestMemberIsDefined(stream.pli_count);
@@ -510,9 +510,12 @@
     verifier.TestMemberIsOptionalIDReference(
         transport.rtcp_transport_stats_id, RTCTransportStats::kType);
     verifier.TestMemberIsDefined(transport.active_connection);
-    verifier.TestMemberIsDefined(transport.selected_candidate_pair_id);
-    verifier.TestMemberIsDefined(transport.local_certificate_id);
-    verifier.TestMemberIsDefined(transport.remote_certificate_id);
+    verifier.TestMemberIsIDReference(
+        transport.selected_candidate_pair_id, RTCIceCandidatePairStats::kType);
+    verifier.TestMemberIsIDReference(
+        transport.local_certificate_id, RTCCertificateStats::kType);
+    verifier.TestMemberIsIDReference(
+        transport.remote_certificate_id, RTCCertificateStats::kType);
     return verifier.ExpectAllMembersSuccessfullyTested();
   }