title: Error: Components.utils undefined - Firefox Add-on
body: <p>I am developing a Firefox add-on (using add-on SDK) and I need to use cookies. In order to do that I should import the <a href="https://developer.mozilla.org/en-US/docs/Mozilla/JavaScript_code_modules/Services.jsm" rel="nofollow">"Services.jsm"</a> module.</p>
  
  <p>I have followed the instructions from MDN, which advises to use</p>
  
  <pre><code>Components.utils.import("resource://gre/modules/Services.jsm");
  </code></pre>
  
  <p>I also tried:</p>
  
  <pre><code>Components.utils["import"]("resource://gre/modules/Services.jsm");
  </code></pre>
  
  <p>When using both I get: </p>
  
  <pre><code>- _errorType = TypeError
  - message = Components.utils is undefined
  </code></pre>
  
  <p>Does any one know how to solve this?</p>
  
  <p>References:
  <a href="https://developer.mozilla.org/en-US/docs/Mozilla/Tech/XPCOM/Language_Bindings/Components.utils.import" rel="nofollow">Components.utils.import</a></p>