[Sync] Create new top-level sync/ directory

chrome/chrome_browser_extensions.gypi

 # 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.
 
 {
   'targets': [
     {
       'target_name': 'browser_extensions',
       'type': 'static_library',
       'variables': { 'enable_wexit_time_destructors': 1, },
       'dependencies': [
         'app/policy/cloud_policy_codegen.gyp:policy',
         'autofill_regexes',
-        'browser/sync/protocol/sync_proto.gyp:sync_proto',
+        '../sync/protocol/sync_proto.gyp:sync_proto',
         'cert_logger_proto',
         'chrome_resources.gyp:chrome_extra_resources',
         'chrome_resources.gyp:chrome_resources',
         'chrome_resources.gyp:chrome_strings',
         'chrome_resources.gyp:platform_locale_settings',
         'chrome_resources.gyp:theme_resources',
         'common',
         'common/extensions/api/api.gyp:api',
         'common_net',
         'debugger',
@@ skipping 671 matching lines @@
                 }],
               ],
             }],
           ],
         }],
       ],
     },
   ],
 }