title: registerIdlingResources deprecation replacement doesn't work
body: <p>I'm trying to replace my Espresso <code>registerIdlingResources</code> and <code>unregisterIdlingResources</code> deprecated method by using <code>IdlingRegistry</code> method according to android documentation.</p>
  
  <p>Some of my tests worked before the update and no longer works now... These tests work unitarily but not together.</p>
  
  <p>I noticed that there is a little difference with the old version (of <code>Espresso</code> class), this line is not present in <code>IdlingRegistry</code> class :</p>
  
  <pre><code>baseRegistry.sync(IdlingRegistry.getInstance().getResources(), IdlingRegistry.getInstance().getLoopers());
  </code></pre>
  
  <p>I think this <code>sync</code> method is very important for my custom IdlingResource...</p>
  
  <p>How can I sync my looper without this line ? </p>
  
  <p>Thanks you for your help.</p>
  
  <p>Edit: I use EspressoCore 3.0.1 with runner/rules 1.0.1</p>
  
  <p>Edit2: Link of documentation who has been specify deprecation : <a href="https://developer.android.com/reference/android/support/test/espresso/Espresso.html#registerIdlingResources(android.support.test.espresso.IdlingResource...)" rel="noreferrer">Here</a> and <a href="https://developer.android.com/reference/android/support/test/espresso/Espresso.html#unregisterIdlingResources(android.support.test.espresso.IdlingResource...)" rel="noreferrer">Here</a>.</p>