Add first implemenation for SU password sync

chrome/browser/chromeos/login/fake_supervised_user_manager.cc

 // Copyright 2013 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 "chrome/browser/chromeos/login/fake_supervised_user_manager.h"
 
 #include <string>
 
 namespace chromeos {
 
@@ skipping 37 matching lines @@
 std::string FakeSupervisedUserManager::GetManagerUserId(
     const std::string& managed_user_id) const {
   return std::string();
 }
 
 std::string FakeSupervisedUserManager::GetManagerDisplayEmail(
     const std::string& managed_user_id) const {
   return std::string();
 }
 
+SupervisedUserAuthentication* FakeSupervisedUserManager::GetAuthentication() {
+  return NULL;
+}
+
 }  // namespace chromeos