[Chromoting] Move SharedSecretHash from Me2MeHostAuthenticatorFactory to AuthenticationMethod.

remoting/protocol/authentication_method.h

 // Copyright (c) 2012 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.
 
 // AuthenticationMethod represents an authentication algorithm and its
 // configuration. It knows how to parse and format authentication
 // method names.
 // Currently the following methods are supported:
 //   v1_token - deprecated V1 authentication mechanism,
 //   spake2_plain - SPAKE2 without hashing applied to the password.
@@ skipping 51 matching lines @@
   }
 
  private:
   AuthenticationMethod();
   AuthenticationMethod(HashFunction hash_function);
 
   bool invalid_;
   HashFunction hash_function_;
 };
 
+// SharedSecretHash stores hash of a host secret paired with the type
+// of the hashing function.
+struct SharedSecretHash {
+  AuthenticationMethod::HashFunction hash_function;
+  std::string value;
+
+  // Parse string representation of a shared secret hash. The |as_string|
+  // must be in form "<hash_function>:<hash_value_base64>".
+  bool Parse(const std::string& as_string);
+};
+
 }  // namespace protocol
 }  // namespace remoting
 
 #endif  // REMOTING_PROTOCOL_AUTHENTICATION_METHOD_H_