Singleton must be created on request

The creation of singleton relies on the `userData` dir, which can be
changed by user, we have to ensure singleton uses the `userData` dir set
by user.

chromium_src/chrome/browser/process_singleton_win.cc

@@ -182,8 +182,11 @@ bool TerminateAppWithError() {
 
 }  // namespace
 
-ProcessSingleton::ProcessSingleton(const base::FilePath& user_data_dir)
-    : is_virtualized_(false),
+ProcessSingleton::ProcessSingleton(
+    const base::FilePath& user_data_dir,
+    const NotificationCallback& notification_callback)
+    : notification_callback_(notification_callback),
+      is_virtualized_(false),
       lock_file_(INVALID_HANDLE_VALUE),
       user_data_dir_(user_data_dir),
       should_kill_remote_process_callback_(base::Bind(&TerminateAppWithError)) {