make new syncer thread the default.

chrome/browser/sync/profile_sync_factory_impl.cc

Index: chrome/browser/sync/profile_sync_factory_impl.cc
diff --git a/chrome/browser/sync/profile_sync_factory_impl.cc b/chrome/browser/sync/profile_sync_factory_impl.cc
index b272f20b6dbf15695875285d63097fd893bad05f..9102e88aaaff9dd08e3c23cad36ed559017f0fc2 100644
--- a/chrome/browser/sync/profile_sync_factory_impl.cc
+++ b/chrome/browser/sync/profile_sync_factory_impl.cc
@@ -16,7 +16,6 @@
 #include "chrome/browser/sync/glue/bookmark_data_type_controller.h"
 #include "chrome/browser/sync/glue/bookmark_model_associator.h"
 #include "chrome/browser/sync/glue/data_type_manager_impl.h"
-#include "chrome/browser/sync/glue/data_type_manager_impl2.h"
 #include "chrome/browser/sync/glue/extension_change_processor.h"
 #include "chrome/browser/sync/glue/extension_data_type_controller.h"
 #include "chrome/browser/sync/glue/extension_model_associator.h"
@@ -55,7 +54,6 @@ using browser_sync::BookmarkModelAssociator;
 using browser_sync::DataTypeController;
 using browser_sync::DataTypeManager;
 using browser_sync::DataTypeManagerImpl;
-using browser_sync::DataTypeManagerImpl2;
 using browser_sync::ExtensionChangeProcessor;
 using browser_sync::ExtensionDataTypeController;
 using browser_sync::ExtensionModelAssociator;
@@ -161,10 +159,7 @@ ProfileSyncService* ProfileSyncFactoryImpl::CreateProfileSyncService(
 DataTypeManager* ProfileSyncFactoryImpl::CreateDataTypeManager(
     SyncBackendHost* backend,
     const DataTypeController::TypeMap& controllers) {
-  if (command_line_->HasSwitch(switches::kNewSyncerThread))
-    return new DataTypeManagerImpl2(backend, controllers);
-  else
-    return new DataTypeManagerImpl(backend, controllers);
+  return new DataTypeManagerImpl(backend, controllers);
 }
 
 ProfileSyncFactory::SyncComponents