Examine source code of Twitch Follow

{
  "name": "Twitch Follow",
  "version": "1.2",
  "description": "Custom twitch alert",
  "author": "Oumbra",
  "manifest_version": 2,
  "permissions": [
    "notifications",
    "storage"
  ],
  "web_accessible_resources": [
    "assets/*.png"
  ],
  "background": {
    "scripts": [
      "background-native.js",
      "runtime.js"
    ]
  },
  "browser_action": {
    "default_popup": "index.html",
    "default_icon": "assets/twitch-flat.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{548749a8-de1b-4654-b9a3-baa7d8c673ab}"
    }
  }
}