Examine source code of WP Detective

{
  "manifest_version": 2,
  "name": "WP Detective",
  "description": "Find out what theme and plugins the WordPress sites you visit are using",
  "version": "1.2resigned1",
  "icons": {
    "16": "icons/icon-16.png",
    "48": "icons/icon-48.png",
    "128": "icons/icon-128.png"
  },
  "permissions": [
    "tabs",
    "*://wpdetective.app/*",
    "*://wpdetective.io/*"
  ],
  "background": {
    "scripts": [
      "browser-polyfill.js",
      "crc32.js",
      "domain-blacklist.js",
      "background.js"
    ]
  },
  "page_action": {
    "default_icon": {
      "19": "icons/icon-19.png",
      "38": "icons/icon-38.png"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{76149e08-c52a-4343-a677-3ed5790f4d05}"
    }
  }
}