Remove deprecated ssl_identity methods

This is a followup to
https://webrtc-review.googlesource.com/c/src/+/170637

Bug: webrtc:11450
Change-Id: I69928ed7236c6a8a569c7dc0383f7debb4408179
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/171224
Commit-Queue: Harald Alvestrand <hta@webrtc.org>
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#31086}
diff --git a/pc/stats_collector_unittest.cc b/pc/stats_collector_unittest.cc
index c6b57c2..471f382 100644
--- a/pc/stats_collector_unittest.cc
+++ b/pc/stats_collector_unittest.cc
@@ -682,8 +682,7 @@
 
     // Fake certificate to report.
     rtc::scoped_refptr<rtc::RTCCertificate> local_certificate(
-        rtc::RTCCertificate::Create(
-            std::unique_ptr<rtc::SSLIdentity>(local_identity.GetReference())));
+        rtc::RTCCertificate::Create(local_identity.Clone()));
     pc->SetLocalCertificate(kTransportName, local_certificate);
     pc->SetRemoteCertChain(kTransportName,
                            remote_identity.cert_chain().Clone());