Enable the syncing of extension and app settings by default.

chrome/browser/sync/profile_sync_components_factory_impl.cc

Index: chrome/browser/sync/profile_sync_components_factory_impl.cc
diff --git a/chrome/browser/sync/profile_sync_components_factory_impl.cc b/chrome/browser/sync/profile_sync_components_factory_impl.cc
index 70dc4cd78eeae13d3438215cbf14e3bd21b34d4f..a2bff650850b971eb97ef2878ee86785b4f4e1ff 100644
--- a/chrome/browser/sync/profile_sync_components_factory_impl.cc
+++ b/chrome/browser/sync/profile_sync_components_factory_impl.cc
@@ -161,12 +161,17 @@ void ProfileSyncComponentsFactoryImpl::RegisterDataTypes(
         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));