[Chromoting] Move SharedSecretHash from Me2MeHostAuthenticatorFactory to AuthenticationMethod.

remoting/protocol/authentication_method.h

Index: remoting/protocol/authentication_method.h
diff --git a/remoting/protocol/authentication_method.h b/remoting/protocol/authentication_method.h
index 6702187c337b7bd6c2e911a9e572ea2ba5187c8d..a4f003e8311d1322d33bcf9880db251b33b8c4a5 100644
--- a/remoting/protocol/authentication_method.h
+++ b/remoting/protocol/authentication_method.h
@@ -69,6 +69,17 @@ class AuthenticationMethod {
   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