chrome_darkmode/background.js

chrome.browserAction.onClicked.addListener(function(tab) {
    chrome.tabs.query({ active: true, currentWindow: true }, function(tabs) {
      var tab = tabs[0];
      var url = tab.url;
  
      if (url === 'chrome://flags/#enable-force-dark') {
        chrome.tabs.update(tab.id, { url: 'chrome://flags/' });
      } else {
        chrome.tabs.update(tab.id, { url: 'chrome://flags/#enable-force-dark' });
      }
    });
  });