chrome.runtime.onInstalled.addListener(function() {
  chrome.storage.sync.set({color: '#3aa757'}, function() {
    console.log("The color is green.");
  });

  chrome.declarativeContent.onPageChanged.removeRules(undefined, function() {
    chrome.declarativeContent.onPageChanged.addRules([{
      conditions: [new chrome.declarativeContent.PageStateMatcher({
        pageUrl: {hostEquals: 'developer.chrome.com'},
      })
      ],
      actions: [new chrome.declarativeContent.ShowPageAction()]
    }]);
  });

  let i = 0;
  setInterval(() => {
    console.log(`${++i}s since start`)
  }, 1000);
});