Examine source code of Domain in tab

{
  "manifest_version": 2,
  "name": "Domain in tab",
  "description": "This extension add domain to the tab title.",
  "version": "1.2.2resigned1",
  "icons": {
    "128": "128x128.png"
  },
  "applications": {
    "gecko": {
      "id": "{1f70ccf0-e9a8-449c-87e7-d44e5411955f}"
    }
  },
  "content_scripts": [
    {
      "matches": [
        "*://*/*"
      ],
      "js": [
        "dit.js"
      ]
    }
  ]
}