title: Chrome extension and XHR with permission
body: <p>I'm working on a Chrome extension and I've some issue with a XHR cross-domain. Let me explain: I set right permission in <code>manifest.json</code> for a domain and I make (in my js file) a simple XMLHttpRequest. Request works fine but <code>responseXML</code> field is <code>null</code>. Why? It is not an issue with SOP and <code>responseText</code> correctly contains HTML text of the page requested. How I can parse it? I can't do it with <code>DOMParser().parseFromString</code>even with using <a href="https://developer.mozilla.org/en/DOMParser" rel="nofollow">https://developer.mozilla.org/en/DOMParser</a> implementation, I receive everytime a single.</p>
  
  <p>Some suggestions? My (simple) code is following:</p>
  
  <pre><code>var req = new XMLHttpRequest();
  req.open("GET", "http://somedomain.com", true);
  
  req.overrideMimeType("text/xml");
  req.setRequestHeader("Content-Type", "text/xml");
  req.onload = anonymousFunction;
  
  req.send(null);
  </code></pre>
  
  <p>Thanks for any replies!</p>