Examine source code of Shortener

{
  "manifest_version": 2,
  "name": "Shortener",
  "version": "0.2.0",
  "description": "Generate short-lived, human-readable URLs in one click. Official browser extension for Shortener.",
  "homepage_url": "https://github.com/lltr",
  "icons": {
    "48": "icon.png"
  },
  "permissions": [
    "tabs",
    "activeTab",
    "https://ex.gy/create"
  ],
  "browser_action": {
    "default_icon": "icon.png",
    "default_title": "Shortener",
    "default_popup": "popup.html",
    "browser_style": true
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{af51db4b-43f3-48ff-9035-989b7c8cf72c}"
    }
  }
}