Revert of Replacing DtlsIdentityStoreInterface with RTCCertificateGeneratorInterface.

webrtc/api/java/jni/peerconnection_jni.cc

Index: webrtc/api/java/jni/peerconnection_jni.cc
diff --git a/webrtc/api/java/jni/peerconnection_jni.cc b/webrtc/api/java/jni/peerconnection_jni.cc
index 9e89492c6378035cee2e155379fa5a1987944de0..522ae756b717951696bcd3055312de5e1701ea15 100644
--- a/webrtc/api/java/jni/peerconnection_jni.cc
+++ b/webrtc/api/java/jni/peerconnection_jni.cc
@@ -1603,11 +1603,7 @@
   PCOJava* observer = reinterpret_cast<PCOJava*>(observer_p);
   observer->SetConstraints(new ConstraintsWrapper(jni, j_constraints));
   rtc::scoped_refptr<PeerConnectionInterface> pc(f->CreatePeerConnection(
-      rtc_config,
-      observer->constraints(),
-      nullptr,
-      std::unique_ptr<rtc::RTCCertificateGeneratorInterface>(),
-      observer));
+      rtc_config, observer->constraints(), NULL, NULL, observer));
   return (jlong)pc.release();
 }