When a user logs into sync, the appropriate cookies are retrieved so that

chrome/browser/about_flags.cc

 // 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.
 
 #include "chrome/browser/about_flags.h"
 
 #include <algorithm>
 #include <iterator>
 #include <map>
 #include <set>
@@ skipping 307 matching lines @@
     SINGLE_VALUE_TYPE(switches::kLevelDBIndexedDatabase)
   },
   {
     "preload-instant-search",
     IDS_FLAGS_PRELOAD_INSTANT_SEARCH_NAME,
     IDS_FLAGS_PRELOAD_INSTANT_SEARCH_DESCRIPTION,
     kOsAll,
     SINGLE_VALUE_TYPE(switches::kPreloadInstantSearch)
   },
   {
+    "disable-auto-login",
+    IDS_FLAGS_AUTO_LOGIN_NAME,
+    IDS_FLAGS_AUTO_LOGIN_DESCRIPTION,
+    kOsMac | kOsWin | kOsLinux,
+    SINGLE_VALUE_TYPE(switches::kDisableAutoLogin)
+  },
+  {
     "static-ip-config",
     IDS_FLAGS_STATIC_IP_CONFIG_NAME,
     IDS_FLAGS_STATIC_IP_CONFIG_DESCRIPTION,
     kOsCrOS,
 #if defined(OS_CHROMEOS)
     // This switch exists only on Chrome OS.
     SINGLE_VALUE_TYPE(switches::kEnableStaticIPConfig)
 #else
     SINGLE_VALUE_TYPE("")
 #endif
@@ skipping 438 matching lines @@
 }
 
 const Experiment* GetExperiments(size_t* count) {
   *count = num_experiments;
   return experiments;
 }
 
 }  // namespace testing
 
 }  // namespace about_flags