Allow TransportController to create a QuicTransportChannel

webrtc/base/sslfingerprint.cc

 /*
  *  Copyright 2012 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 67 matching lines @@
 }
 
 std::string SSLFingerprint::GetRfc4572Fingerprint() const {
   std::string fingerprint =
       rtc::hex_encode_with_delimiter(digest.data<char>(), digest.size(), ':');
   std::transform(fingerprint.begin(), fingerprint.end(),
                  fingerprint.begin(), ::toupper);
   return fingerprint;
 }
 
-std::string SSLFingerprint::ToString() {
+std::string SSLFingerprint::ToString() const {
   std::string fp_str = algorithm;
   fp_str.append(" ");
   fp_str.append(GetRfc4572Fingerprint());
   return fp_str;
 }
 
 }  // namespace rtc