title: How to handle js popup dialogs in chrome extension
body: <p>I need to know in a chrome extension when a JS popup window, like an alert or confirm dialog, is opened. </p>
  
  <p>I have the following questions:</p>
  
  <ol>
  <li>Is there any chrome.* api or other api for this?</li>
  <li>Are these kinds of dialogs a specific chrome.window object?</li>
  </ol>
  
  <p>Thanks.</p>