title: Chrome extension uninstall URL not working in all cases
body: <p>I track my extension uninstalls using the method chrome.runtime.setUninstallURL</p>
  
  <p>It has been working fine for months but recently I noticed that if I remove the extension from the Chrome Webstore page (e.g. <a href="https://chrome.google.com/webstore/detail/" rel="nofollow noreferrer">https://chrome.google.com/webstore/detail/</a>{ext_name}/{ext_id}), then the uninstall URL is not opened. </p>
  
  <p>Has something changed in the runtime API? Is this now expected behaviour?</p>