title: Access extensions in the chrome://extensions page
body: <p>Here is my <code>mainfest.json</code>:</p>
  
  <pre><code>"content_scripts": [ {
      "all_frames": true,
      "css": [ "css/event.css" ],
      "matches": [ "\u003Call_urls&gt;" ],
      "run_at": "document_start"
  }
  </code></pre>
  
  <p>but I cannot find content script in the <code>chrome://extensions/</code> page<br>
  help!!!</p>