Examine source code of Coupon Stack

{
  "manifest_version": 3,
  "name": "Coupon Stack",
  "version": "1.0",
  "description": "Apply a percent coupon then a flat discount and show the checkout total.",
  "icons": {
    "128": "icon.png"
  },
  "action": {
    "default_title": "Coupon Stack",
    "default_popup": "popup.html",
    "default_icon": "icon.png"
  },
  "permissions": [],
  "browser_specific_settings": {
    "gecko": {
      "id": "emircannonnmkb@hotmail.com",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  }
}