[Sync] use base::Time in sync

chrome/chrome.gyp

 # Copyright (c) 2011 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,
 
     'variables': {
       'version_py_path': 'tools/build/version.py',
       'version_path': 'VERSION',
@@ skipping 683 matching lines @@
         'browser/sync/util/extensions_activity_monitor.h',
         'browser/sync/util/immutable.h',
         'browser/sync/util/logging.cc',
         'browser/sync/util/logging.h',
         'browser/sync/util/nigori.cc',
         'browser/sync/util/nigori.h',
         'browser/sync/util/oauth.cc',
         'browser/sync/util/oauth.h',
         'browser/sync/util/sqlite_utils.cc',
         'browser/sync/util/sqlite_utils.h',
+        'browser/sync/util/time.cc',
+        'browser/sync/util/time.h',
         'browser/sync/util/user_settings.cc',
         'browser/sync/util/user_settings.h',
         'browser/sync/util/user_settings_posix.cc',
         'browser/sync/util/user_settings_win.cc',
         'browser/sync/util/weak_handle.cc',
         'browser/sync/util/weak_handle.h',
       ],
       'include_dirs': [
         '..',
       ],
@@ skipping 989 matching lines @@
             'destination': '<(PRODUCT_DIR)',
             'files': [
               '<(INTERMEDIATE_DIR)/repack/chrome.pak'
             ],
           },
         ],
       }],  # targets
     }],  # OS != "mac"
   ],  # 'conditions'
 }