Enable the syncing of extension and app settings by default.

chrome/browser/sync/profile_sync_components_factory_impl.cc

 // 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.
 
 #include "base/command_line.h"
 #include "chrome/browser/extensions/app_notification_manager.h"
 #include "chrome/browser/extensions/extension_service.h"
 #include "chrome/browser/extensions/settings/settings_frontend.h"
 #include "chrome/browser/prefs/pref_model_associator.h"
 #include "chrome/browser/profiles/profile.h"
@@ skipping 143 matching lines @@
         new SearchEngineDataTypeController(this, profile_, pss));
   }
 
   // Session sync is disabled by default.  Register only if explicitly
   // enabled.
   if (command_line_->HasSwitch(switches::kEnableSyncTabs)) {
     pss->RegisterDataTypeController(
         new SessionDataTypeController(this, profile_, pss));
   }
 
-  // Extension setting sync is disabled by default.  Register only if
-  // explicitly enabled.
-  if (command_line_->HasSwitch(switches::kEnableSyncExtensionSettings)) {
+  // Extension setting sync is enabled by default.  Register unless explicitly
+  // disabled.
+  if (!command_line_->HasSwitch(switches::kDisableSyncExtensionSettings)) {
     pss->RegisterDataTypeController(
         new ExtensionSettingDataTypeController(
             syncable::EXTENSION_SETTINGS, this, profile_, pss));
+  }
+
+  // App setting sync is enabled by default.  Register unless explicitly
+  // disabled.
+  if (!command_line_->HasSwitch(switches::kDisableSyncAppSettings)) {
     pss->RegisterDataTypeController(
         new ExtensionSettingDataTypeController(
             syncable::APP_SETTINGS, this, profile_, pss));
   }
 
   if (!command_line_->HasSwitch(switches::kDisableSyncAutofillProfile)) {
     pss->RegisterDataTypeController(
         new AutofillProfileDataTypeController(this, profile_, pss));
   }
 
@@ skipping 239 matching lines @@
   GenericChangeProcessor* change_processor =
       new GenericChangeProcessor(error_handler,
                                  notif_sync_service,
                                  user_share);
   SyncableServiceAdapter* sync_service_adapter =
       new SyncableServiceAdapter(syncable::APP_NOTIFICATIONS,
                                  notif_sync_service,
                                  change_processor);
   return SyncComponents(sync_service_adapter, change_processor);
 }