Return nullptr from RTCCertificate::FromPEM on failure.

webrtc/base/rtccertificate.h

 /*
  *  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 48 matching lines @@
   const SSLCertificate& ssl_certificate() const;
 
   // TODO(hbos): If possible, remove once RTCCertificate and its
   // ssl_certificate() is used in all relevant places. Should not pass around
   // raw SSLIdentity* for the sake of accessing SSLIdentity::certificate().
   // However, some places might need SSLIdentity* for its public/private key...
   SSLIdentity* identity() const { return identity_.get(); }
 
   // To/from PEM, a text representation of the RTCCertificate.
   RTCCertificatePEM ToPEM() const;
+  // Can return nullptr if the certificate is invalid.
   static scoped_refptr<RTCCertificate> FromPEM(const RTCCertificatePEM& pem);
   bool operator==(const RTCCertificate& certificate) const;
   bool operator!=(const RTCCertificate& certificate) const;
 
  protected:
   explicit RTCCertificate(SSLIdentity* identity);
   ~RTCCertificate() override;
 
  private:
   // The SSLIdentity is the owner of the SSLCertificate. To protect our
   // ssl_certificate() we take ownership of |identity_|.
   std::unique_ptr<SSLIdentity> identity_;
 };
 
 }  // namespace rtc
 
 #endif  // WEBRTC_BASE_RTCCERTIFICATE_H_