Examine source code of Anime Notifier

{
  "name": "Anime Notifier",
  "short_name": "Anime Notifier",
  "version": "2.1.1resigned1",
  "manifest_version": 2,
  "description": "Notifies you when there's a new episode of your favourite anime available.",
  "homepage_url": "https://notify.moe/",
  "options_page": "options.html",
  "offline_enabled": true,
  "icons": {
    "64": "icons/64.png",
    "128": "icons/128.png",
    "220": "icons/220.png"
  },
  "permissions": [
    "https://notify.moe/"
  ],
  "browser_action": {
    "default_icon": "icons/64.png",
    "default_popup": "popup.html"
  },
  "applications": {
    "gecko": {
      "id": "extension@notify.moe",
      "strict_min_version": "44.0"
    }
  }
}