Examine source code of Shopping Cart Import

{
  "manifest_version": 3,
  "author": "Slingshot Software Inc",
  "name": "Shopping Cart Import",
  "version": "2.0",
  "description": "Shopping Cart contents import into Slingshot",
  "homepage_url": "https://www.slingshotsoftware.com",
  "icons": {
    "32": "icons/cartimport32.png",
    "40": "icons/cartimport40.png",
    "48": "icons/cartimport48.png",
    "64": "icons/cartimport64.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "cartimport@slingshotdevelopment.com"
    }
  },
  "permissions": [
    "activeTab",
    "scripting",
    "storage"
  ],
  "action": {
    "default_icon": {
      "20": "icons/cartimport40.png",
      "32": "icons/cartimport32.png",
      "40": "icons/cartimport40.png",
      "48": "icons/cartimport48.png"
    },
    "default_title": "Shopping Cart Import"
  },
  "background": {
    "scripts": [
      "handler.js"
    ]
  },
  "options_ui": {
    "page": "setup/settings.html"
  }
}