Examine source code of Google Hello World

{
  "manifest_version": 2,
  "name": "Test",
  "version": "1.0",
  "description": "Testing out the extensions in Firefox!",
  "content_scripts": [
    {
      "matches": [
        "*://*.google.com/*"
      ],
      "js": [
        "test.js"
      ]
    }
  ]
}