Revert of Replacing DtlsIdentityStoreInterface with RTCCertificateGeneratorInterface.

webrtc/api/peerconnectioninterface_unittest.cc

Index: webrtc/api/peerconnectioninterface_unittest.cc
diff --git a/webrtc/api/peerconnectioninterface_unittest.cc b/webrtc/api/peerconnectioninterface_unittest.cc
index 8ced9a784153711f5b1ab0e344ed1375984c39c5..d2f0ad1c56eec69a1e0fb36e540fb5d3236c2df2 100644
--- a/webrtc/api/peerconnectioninterface_unittest.cc
+++ b/webrtc/api/peerconnectioninterface_unittest.cc
@@ -616,12 +616,8 @@
     config.servers.push_back(server);
 
     scoped_refptr<PeerConnectionInterface> pc;
-    pc = pc_factory_->CreatePeerConnection(
-        config,
-        nullptr,
-        nullptr,
-        std::unique_ptr<rtc::RTCCertificateGeneratorInterface>(),
-        &observer_);
+    pc = pc_factory_->CreatePeerConnection(config, nullptr, nullptr, nullptr,
+                                           &observer_);
     EXPECT_EQ(nullptr, pc);
   }