Examine source code of Amazon Wishlist Total

{
  "author": "Carlos Araoz",
  "manifest_version": 2,
  "name": "Amazon Wishlist Subtotal",
  "description": "Sums up all of your wishlist items prices and displays it at the top of the wishlist",
  "version": "0.2.0",
  "permissions": [
    "activeTab"
  ],
  "content_scripts": [
    {
      "matches": [
        "*://*.amazon.com/*",
        "*://*.amazon.com.mx/*",
        "*://*.amazon.com.au/*",
        "*://*.amazon.com.be/*",
        "*://*.amazon.com.tr/*",
        "*://*.amazon.co.jp/*",
        "*://*.amazon.ca/*",
        "*://*.amazon.de/*",
        "*://*.amazon.eg/*",
        "*://*.amazon.in/*",
        "*://*.amazon.it/*",
        "*://*.amazon.nl/*",
        "*://*.amazon.pl/*",
        "*://*.amazon.sa/*",
        "*://*.amazon.sg/*",
        "*://*.amazon.se/*"
      ],
      "js": [
        "src/subtotal.js"
      ],
      "run_at": "document_end"
    }
  ],
  "icons": {
    "16": "images/icon-16.png",
    "32": "images/icon-32.png",
    "64": "images/icon-64.png",
    "128": "images/icon-128.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{8b2cf240-ea17-401a-8465-1dcddaa75704}"
    }
  }
}