Revert of Replacing DtlsIdentityStoreInterface with RTCCertificateGeneratorInterface.

talk/app/webrtc/objc/RTCPeerConnection.mm

Index: talk/app/webrtc/objc/RTCPeerConnection.mm
diff --git a/talk/app/webrtc/objc/RTCPeerConnection.mm b/talk/app/webrtc/objc/RTCPeerConnection.mm
index 6ec7edcdc92699255d9e776ea57fd055935c4a54..da092c80269b6c378bdb2aaf6f0a726bf70d7aa8 100644
--- a/talk/app/webrtc/objc/RTCPeerConnection.mm
+++ b/talk/app/webrtc/objc/RTCPeerConnection.mm
@@ -279,11 +279,7 @@
     config.servers = iceServers;
     _observer.reset(new webrtc::RTCPeerConnectionObserver(self));
     _peerConnection = factory->CreatePeerConnection(
-        config,
-        constraints,
-        nullptr,
-        std::unique_ptr<rtc::RTCCertificateGeneratorInterface>(),
-        _observer.get());
+        config, constraints, nullptr, nullptr, _observer.get());
     _localStreams = [[NSMutableArray alloc] init];
   }
   return self;
@@ -297,12 +293,7 @@
   if (self = [super init]) {
     _observer.reset(new webrtc::RTCPeerConnectionObserver(self));
     _peerConnection =
-        factory->CreatePeerConnection(
-            config,
-            constraints,
-            nullptr,
-            std::unique_ptr<rtc::RTCCertificateGeneratorInterface>(),
-            _observer.get());
+        factory->CreatePeerConnection(config, constraints, nullptr, nullptr, _observer.get());
     _localStreams = [[NSMutableArray alloc] init];
     _delegate = delegate;
   }