title: Cross-domain XMLHttpRequest using background pages
body: <p>In my Chrome extension, I want to have my <code>options.html</code> page communicate with something like Google's OpenId API. In order to do this seamlessly, I have a hidden <code>iframe</code> on the options page which will pop-up the Google Accounts login page (following the OpenId interaction sequence, etc.).</p>
  
  <p>My issue is that I can't communicate from the options page to the <code>iframe</code> (the origin of the <code>iframe</code> is something I control, but not the same as my chrome extension) via <code>window.postMessage</code>. I was wondering if there is a quick workaround to this issue.</p>
  
  <p>If there isn't, I'm going to make <code>options.html</code> contain an <code>iframe</code> that houses the layout and logic of the page.</p>