fs-watcher: Fixed fs-watcher multiple onChange callback

Change-Id: Ied8c876e4fee238c960e091466e275823e83e899
diff --git a/scheduler/scheduler.h b/scheduler/scheduler.h
index 096be98..a52649a 100644
--- a/scheduler/scheduler.h
+++ b/scheduler/scheduler.h
@@ -70,6 +70,10 @@
   schedulePeriodicTask (SchedulerPtr scheduler, IntervalGeneratorPtr delayGenerator,
                         const Task::Callback &callback, const Task::Tag &tag);
 
+  // helper method to schedule/reschedule one-time task
+  static TaskPtr
+  scheduleDelayOneTimeTask (SchedulerPtr scheduler, double delay, const Task::Callback &callback, const Task::Tag &tag);
+
   // if task with the same tag exists, the task is not added and return false
   virtual bool
   addTask(TaskPtr task, bool reset = true);