Examine source code of Cleartext

{
  "manifest_version": 2,
  "name": "Cleartext",
  "description": "Displays text in a clear way",
  "version": "1.2.1",
  "icons": {
    "48": "icons/image-48.png"
  },
  "permissions": [
    "menus",
    "activeTab"
  ],
  "background": {
    "scripts": [
      "script.js"
    ]
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{674384ff-8e5e-4834-9aff-9723190c68b8}"
    }
  }
}