title: Check if user has a third party Chrome extension installed
body: <p>I am currently trying to detect if a user has a certain Chrome extension installed. The Chrome extension is not my own and I do not have the source code to it. I have tried methods in numerous posts but they all fail. What I've tried and why it failed is detailed below.</p>
  
  <p>This results in 'cannot read property connect of undefined' when executed:</p>
  
  <pre><code>var myPort=chrome.extension.connect('idldbjenlmipmpigmfamdlfifkkeaplc', some_object_to_send_on_connect);
  </code></pre>
  
  <p>Trying to load a resource of the extension as follows to test if it's there but going to this URL in browser results in 'your file was not found' Chrome error page (note that I found this path by going to C:\Users\\AppData\Local\Google\Chrome\User Data\Default\Extensions\idldbjenlmipmpigmfamdlfifkkeaplc\1.0.0.1_0\ on my Windows local machine):</p>
  
  <pre><code>chrome-extension://idldbjenlmipmpigmfamdlfifkkeaplc/1.0.0.1_0/icon_16.png
  </code></pre>
  
  <p>Using Chrome management but this results in console error 'cannot read property get of undefined' when executed</p>
  
  <pre><code>chrome.management.get("idldbjenlmipmpigmfamdlfifkkeaplc", function(a){console.log(a);});
  </code></pre>
  
  <p>And most other answers I've come across seem to involve the extension being written by the same person who is trying to check for it.</p>