Examine source code of webhint

{
  "author": "webhint",
  "background": {
    "scripts": [
      "background-script.js"
    ]
  },
  "icons": {
    "180": "icon.png"
  },
  "default_locale": "en",
  "description": "Quickly test your website to see if there are any issues with accessibility, browser compatibility, security, performance and more.",
  "devtools_page": "devtools/devtools.html",
  "manifest_version": 2,
  "name": "webhint",
  "permissions": [
    "<all_urls>",
    "webNavigation"
  ],
  "version": "2.4.17",
  "browser_specific_settings": {
    "gecko": {
      "id": "{e748cb59-4901-4bea-b74a-1d8dab98e3c7}"
    }
  }
}