Modify PeerConnection for end-to-end QuicDataChannel usage

webrtc/p2p/base/faketransportcontroller.h

Index: webrtc/p2p/base/faketransportcontroller.h
diff --git a/webrtc/p2p/base/faketransportcontroller.h b/webrtc/p2p/base/faketransportcontroller.h
index a267f209670bf6dc67a1e4859215e491574f22df..6ef3509fbb6fd97ac30473e2b15e9aa0cbb22525 100644
--- a/webrtc/p2p/base/faketransportcontroller.h
+++ b/webrtc/p2p/base/faketransportcontroller.h
@@ -373,9 +373,10 @@ class FakeTransport : public Transport {
     }
   }
 
-  void SetLocalCertificate(
+  bool SetLocalCertificate(
       const rtc::scoped_refptr<rtc::RTCCertificate>& certificate) override {
     certificate_ = certificate;
+    return true;
   }
   bool GetLocalCertificate(
       rtc::scoped_refptr<rtc::RTCCertificate>* certificate) override {