Create background.js

background.js

@@ -0,0 +1,15 @@
+chrome.tabs.onUpdated.addListener(
+  function(tabId, changeInfo, tab) {
+    if (youtube_parser(changeInfo.url)) {
+      chrome.tabs.sendMessage( tabId, {
+        message: 'ytvideo',
+        url: changeInfo.url
+      })
+    }
+  }
+);
+function youtube_parser(url) {
+    var regExp = /^.*((youtu.be\/)|(v\/)|(\/u\/\w\/)|(embed\/)|(watch\?))\??v?=?([^#\&\?]*).*/;
+    var match = url.match(regExp);
+    return (match && match[7].length == 11) ? match[7] : false;
+}