Examine source code of Number Ninja Quest

{
  "manifest_version": 2,
  "name": "Number Ninja Quest",
  "version": "1.0",
  "description": "Sharpen your mental math skills with quick arithmetic challenges. A fun daily brain training popup extension for math lovers.",
  "icons": {
    "48": "number_ninja_icon.png"
  },
  "browser_action": {
    "default_popup": "index.html",
    "default_title": "Number Ninja Quest"
  },
  "permissions": [],
  "browser_specific_settings": {
    "gecko": {
      "id": "{9f8390a7-2cfa-4aba-bd2c-0454a99c9c69}",
      "data_collection_permissions": {
        "required": [
          "none"
        ],
        "optional": []
      }
    }
  }
}