Examine source code of Twitter Private Mode

{
  "manifest_version": 2,
  "name": "Twitter Private Mode",
  "version": "1.0.1",
  "description": "Can show a fake name in place of your name and at on Twitter.com so lookers-on can't stalk your tweets. Allows you to select a random name and at each day from a list you make.",
  "content_scripts": [
    {
      "matches": [
        "*://*.twitter.com/*"
      ],
      "js": [
        "privatize.js"
      ],
      "run_at": "document_start"
    }
  ],
  "permissions": [
    "storage"
  ],
  "browser_action": {
    "default_icon": "icons/private_mode-64.png",
    "default_title": "Twitter Private Mode",
    "default_popup": "popup/index.html",
    "browser_style": true
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{c666bf01-f62b-474e-ace4-30a6889c71c7}"
    }
  }
}