I'm writing a simple Chrome extension that displays a JavaScript alert saying "Hello World". In this example I have specified that the extension will only run for google.com (by putting this in the permissions property within manifest.json). 

Even after everything in the target page has loaded, the alert doesn't appear. Here is my script so far:

**File: manifest.json**

```
{
  "name": "Hello",
  "version": "1.0",
  "description": "Says hello to Google",
  "permissions": ["http://*.google.com/"]
  "browser_action": {
    "popup": "Hello.html"
  }
}

```

**File: Hello.html**

```
<script language="Javascript">
   alert("Hello World");
</script>

```