Examine source code of GooDark

{
  "manifest_version": 2,
  "name": "GooDark",
  "short_name": "GooDark",
  "description": "Google Dark Theme",
  "version": "1.2",
  "applications": {
    "gecko": {
      "id": "{7c89bca0-c350-4499-bda8-4dedca2e79d7}"
    }
  },
  "browser_action": {
    "default_icon": "icon128.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.google.com/*",
        "*://*.google.fr/*"
      ],
      "js": [
        "footer.js",
        "logo.js",
        "background.js",
        "other.js"
      ]
    }
  ],
  "permissions": [
    "tabs",
    "management"
  ],
  "optional_permissions": [],
  "icons": {
    "32": "icon32.png",
    "64": "icon64.png",
    "128": "icon128.png"
  }
}