title: Detect if a Chrome extension is installed
body: <p>I want to detect if a Chrome extension is installed in user's browser. If not, I want to display a link to install the extension. If it is already installed, I want to hide the link.</p>
  
  <p>This seems like a possible solution but I am confused what some_object_to_send_on_connect is supposed to be?
  <a href="https://developer.chrome.com/extensions/extension#global-events" rel="nofollow">https://developer.chrome.com/extensions/extension#global-events</a></p>
  
  <pre><code>var myPort=chrome.extension.connect('jllpkdkcdjndhggodimiphkghogcpida', some_object_to_send_on_connect);
  </code></pre>