displays alert on any new page load

extension/js/background.js

+chrome.tabs.onUpdated.addListener(function (tabID, changeInfo, tab) {
+	if (changeInfo.status=='complete'){
+    		chrome.tabs.sendMessage(tab.id, { action: 'saySomething' });
+	}
+});

extension/js/check.js

 var stop_url = "https://www.google.com/";
 
-chrome.tabs.query({'active': true, 'lastFocusedWindow': true}, function (tabs) {
-        var url = tabs[0].url;
-        if (url == stop_url){
-                document.writeln("welcome to the stop url!");
-        }
-        else {document.writeln("not there yet, keep going");}
+/*chrome.tabs.query({'active': true, 'lastFocusedWindow': true}, function (tabs) {
+	var url = tabs[0].url;
+	if (url == stop_url){
+		document.writeln("welcome to the stop url!");
+	}
+	else {document.writeln("not there yet, keep going");}
 });
-
+*/

extension/js/content.js

+chrome.runtime.onMessage.addListener(function (msg) {
+    /* We received a message, let's do as instructed */
+    if (msg.action == 'saySomething') {
+        window.alert('something');
+    }
+});