Examine source code of Amazon USA Basket button

{
  "manifest_version": 2,
  "name": "Amazon USA Basket",
  "version": "1.0",
  "description": "Amazon USA basket opens in a tab",
  "background": {
    "scripts": [
      "button.js"
    ]
  },
  "browser_action": {
    "default_icon": {
      "48": "icon.png"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{9fbd5775-c27a-4d38-b5c7-7993106349e8}"
    }
  }
}