Examine source code of URL Shortener

{
  "manifest_version": 2,
  "name": "URL Shortener",
  "version": "1.0.2",
  "description": "Extension to select and export your bookmarks as a collection in urlll.xyz!",
  "browser_action": {
    "default_popup": "index.html"
  },
  "permissions": [
    "bookmarks",
    "tabs",
    "storage",
    "https://app.urlll.xyz/*"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "icons": {
    "16": "assets/logo.png",
    "48": "assets/logo.png",
    "128": "assets/logo.png"
  }
}