Examine source code of Animu.com.br

{
  "manifest_version": 2,
  "name": "Animu.com.br",
  "author": "bossatossa",
  "version": "1.1.2",
  "description": "Extensão para ouvires a Animu enquanto navegas a web!",
  "icons": {
    "16": "img/16.png",
    "24": "img/24.png",
    "128": "img/128.png"
  },
  "browser_action": {
    "default_icon": "img/24.png",
    "default_title": "animu.com.br",
    "default_popup": "index.html"
  },
  "options_ui": {
    "page": "options.html",
    "browser_style": true
  },
  "permissions": [
    "storage",
    "webRequest"
  ],
  "background": {
    "persistent": true,
    "scripts": [
      "js/bg.js"
    ]
  },
  "applications": {
    "gecko": {
      "id": "tossa@disroot.org_animuwebext"
    }
  }
}