title: Google maps full screen not showing in a special case
body: <p>I have a webpage that shows google map. It is working fine in standalone mode. Unfortunately when my other website with same domain name calls this page in an iframe, google map div doesn't show the fullscreen control button. All other action buttons are visible and no other bug I found. Below is the code:</p>
  
  <pre><code>var map = new google.maps.Map(
      document.getElementById('map_container'),
      {
          zoom: 5,
          center: center,
          disableDefaultUI: true,
          fullscreenControl: true,   //all other controls works fine
          gestureHandling: 'greedy'
      }
  );
  </code></pre>
  
  <p>EDIT: This is for desktop.</p>
  
  <p>These are two jsfiddle links. One where I create a map and ohter page loads the previous one in an iframe. The full-screen button is missing the the second one.</p>
  
  <ul>
  <li><a href="https://jsfiddle.net/swaroopdeval/ebxv78ot/" rel="nofollow noreferrer">Link of map having full-screen button</a></li>
  <li><a href="https://jsfiddle.net/swaroopdeval/j8cu47mz/" rel="nofollow noreferrer">Link of a page that loads first one in iframe</a></li>
  </ul>