[Cast Channel] Add support for nonce challenge to Cast channel authentication.

extensions/browser/api/cast_channel/cast_message_util.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "extensions/browser/api/cast_channel/cast_message_util.h"
 
 #include <memory>
 
 #include "base/logging.h"
 #include "base/strings/string_number_conversions.h"
@@ skipping 120 matching lines @@
   }
   if (message.has_error()) {
     out += ", error: {";
     out += base::IntToString(message.error().error_type());
     out += "}";
   }
   out += "}";
   return out;
 }
 
-void CreateAuthChallengeMessage(CastMessage* message_proto) {
+void CreateAuthChallengeMessage(CastMessage* message_proto, std::string nonce) {
   CHECK(message_proto);
   DeviceAuthMessage auth_message;
-  auth_message.mutable_challenge();
+  auth_message.mutable_challenge()->set_sender_nonce(nonce);
   std::string auth_message_string;
   auth_message.SerializeToString(&auth_message_string);
 
   message_proto->set_protocol_version(CastMessage_ProtocolVersion_CASTV2_1_0);
   message_proto->set_source_id(kPlatformSenderId);
   message_proto->set_destination_id(kPlatformReceiverId);
   message_proto->set_namespace_(kAuthNamespace);
   message_proto->set_payload_type(CastMessage_PayloadType_BINARY);
   message_proto->set_payload_binary(auth_message_string);
 }
 
 bool IsAuthMessage(const CastMessage& message) {
   return message.namespace_() == kAuthNamespace;
 }
 
 }  // namespace cast_channel
 }  // namespace api
 }  // namespace extensions