title: permission for exported service in android
body: <p>I installed the new android ADT and now I see warnings about exported services defined in the AndroidManifest that do not require a permission. 
  The problem is that the services are related with the sync adapter. In the SampleSyncAdaapter there are no required permissions either but I do not see that warning.</p>
  
  <p>Which permission should I define for the sync adapter?</p>
  
  <p>I have the same problem for the service that handles CLEAR_MISSED_CALLS.</p>