Examine source code of Number Lines Addon

{
  "manifest_version": 2,
  "name": "Number Lines Addon",
  "version": "1.0.1",
  "description": "Insert line numbers for each line of text.",
  "browser_action": {
    "default_title": "Number Lines",
    "default_popup": "popup.html"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "number-lines-addon-bc7cca9b-4a9c-41e7-a5f6-d6bdf080f6d6@example.com",
      "strict_min_version": "58.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  }
}