sync: add WIFI_CREDENTIALS protobuf, ModelType, and preference

sync/sync.gyp

 # 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.
 
 {
   'variables': {
     'chromium_code': 1,
   },
 
   'includes': [
@@ skipping 488 matching lines @@
         'protocol/sync.proto',
         'protocol/sync_enums.proto',
         'protocol/synced_notification_app_info_specifics.proto',
         'protocol/synced_notification_data.proto',
         'protocol/synced_notification_render.proto',
         'protocol/synced_notification_specifics.proto',
         'protocol/test.proto',
         'protocol/theme_specifics.proto',
         'protocol/typed_url_specifics.proto',
         'protocol/unique_position.proto',
+        'protocol/wifi_credential_specifics.proto',
       ],
       'variables': {
         'enable_wexit_time_desctructors': 1,
         'proto_in_dir': './protocol',
         'proto_out_dir': 'sync/protocol',
         'cc_generator_options': 'dllexport_decl=SYNC_PROTO_EXPORT:',
         'cc_include': 'sync/protocol/sync_proto_export.h',
       },
       'includes': [
         '../build/protoc.gypi'
       ],
     },
   ],
 }