message: Make RTCCertificate::identity_ const
  Cr-Commit-Position: refs/heads/master@{#33588}
diff: @@ -87,7 +87,7 @@ class RTC_EXPORT RTCCertificate : public RefCountInterface {
  private:
  // The SSLIdentity is the owner of the SSLCertificate. To protect our
  // GetSSLCertificate() we take ownership of |identity_|.
  - std::unique_ptr<SSLIdentity> identity_;
  + const std::unique_ptr<SSLIdentity> identity_;
  };
  } // namespace rtc
  