Turn app notifications sync to be on by default

chrome/browser/sync/profile_sync_factory_impl.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 "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_backend.h"
 #include "chrome/browser/prefs/pref_model_associator.h"
 #include "chrome/browser/profiles/profile.h"
@@ skipping 165 matching lines @@
     pss->RegisterDataTypeController(
         new ExtensionSettingDataTypeController(
             syncable::APP_SETTINGS, this, profile_, pss));
   }
 
   if (!command_line_->HasSwitch(switches::kDisableSyncAutofillProfile)) {
     pss->RegisterDataTypeController(
         new AutofillProfileDataTypeController(this, profile_));
   }
 
-  // App notifications sync is disabled by default.  Register only if
-  // explicitly enabled.
-  if (command_line_->HasSwitch(switches::kEnableSyncAppNotifications)) {
+  // App notifications sync is enabled by default.  Register only if
+  // explicitly disabled.
+  if (!command_line_->HasSwitch(switches::kDisableSyncAppNotifications)) {
     pss->RegisterDataTypeController(
         new AppNotificationDataTypeController(this, profile_, pss));
   }
 }
 
 DataTypeManager* ProfileSyncFactoryImpl::CreateDataTypeManager(
     SyncBackendHost* backend,
     const DataTypeController::TypeMap* controllers) {
   return new DataTypeManagerImpl(backend, controllers);
 }
@@ skipping 199 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);
 }