Return nullptr from RTCCertificate::FromPEM on failure.

webrtc/base/rtccertificate.cc

 /*
  *  Copyright 2015 The WebRTC Project Authors. All rights reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 36 matching lines @@
 
 RTCCertificatePEM RTCCertificate::ToPEM() const {
   return RTCCertificatePEM(identity_->PrivateKeyToPEMString(),
                            ssl_certificate().ToPEMString());
 }
 
 scoped_refptr<RTCCertificate> RTCCertificate::FromPEM(
     const RTCCertificatePEM& pem) {
   std::unique_ptr<SSLIdentity> identity(SSLIdentity::FromPEMStrings(
       pem.private_key(), pem.certificate()));
+  if (!identity)
+    return nullptr;
   return new RefCountedObject<RTCCertificate>(identity.release());
 }
 
 bool RTCCertificate::operator==(const RTCCertificate& certificate) const {
   return *this->identity_ == *certificate.identity_;
 }
 
 bool RTCCertificate::operator!=(const RTCCertificate& certificate) const {
   return !(*this == certificate);
 }
 
 }  // namespace rtc