[iOS] Add FakeSyncService and factory for testing

components/sync_driver.gypi

 # 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.
 
 {
   'targets': [
     {
       # GN version: //components/sync_driver
       'target_name': 'sync_driver',
       'type': 'static_library',
@@ skipping 87 matching lines @@
         'sync_driver/data_type_controller_mock.cc',
         'sync_driver/data_type_controller_mock.h',
         'sync_driver/data_type_error_handler_mock.cc',
         'sync_driver/data_type_error_handler_mock.h',
         'sync_driver/data_type_manager_mock.cc',
         'sync_driver/data_type_manager_mock.h',
         'sync_driver/fake_data_type_controller.cc',
         'sync_driver/fake_data_type_controller.h',
         'sync_driver/fake_generic_change_processor.cc',
         'sync_driver/fake_generic_change_processor.h',
+        'sync_driver/fake_sync_service.cc',
+        'sync_driver/fake_sync_service.h',
         'sync_driver/local_device_info_provider_mock.cc',
         'sync_driver/local_device_info_provider_mock.h',
         'sync_driver/model_associator_mock.cc',
         'sync_driver/model_associator_mock.h',
         'sync_driver/non_ui_data_type_controller_mock.cc',
         'sync_driver/non_ui_data_type_controller_mock.h',
       ],
     },
   ],
 }