title: IntentService - find number of Intents waiting in the queue
body: <p>In my app I use an IntentService to do some work. I want to find out how many intents are waiting to be processed, as IntentService holds them in a 'work queue' , and sends the next one to <code>onStartCommand()</code> as the <code>onStartCommand</code> of the previous one has finished. </p>
  
  <p>How can I find out how many Intents are waiting in this 'work queue' ?</p>