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()] }]); }); });