Examine source code of Amazon Affiliate Tagger

{
  "description": "Automatically adds one's affiliate tag to the amazon webpage",
  "manifest_version": 2,
  "name": "Amazon Affiliate Tagger",
  "short_name": "AmazonTagger",
  "version": "1.3.2",
  "developer": {
    "name": "Dorian Werner"
  },
  "options_ui": {
    "page": "options.html",
    "browser_style": true
  },
  "icons": {
    "48": "icons/icon_amazon_tag_48.png",
    "64": "icons/icon_amazon_tag_64.png",
    "96": "icons/icon_amazon_tag_96.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.amazon.com/*",
        "*://*.amazon.co.uk/*",
        "*://*.amazon.de/*",
        "*://*.amazon.fr/*",
        "*://*.amazon.co.jp/*",
        "*://*.amazon.ca/*",
        "*://*.amazon.cn/*",
        "*://*.amazon.it/*",
        "*://*.amazon.es/*",
        "*://*.amazon.in/*",
        "*://*.amazon.com.br/*",
        "*://*.amazon.com.mx/*",
        "*://*.amazon.com.au/*",
        "*://*.amazon.ae/*",
        "*://*.amazon.sg/*",
        "*://*.amazon.nl/*",
        "*://*.amazon.sa/*",
        "*://*.amazon.se/*"
      ],
      "js": [
        "affiliatetag.js"
      ],
      "run_at": "document_start"
    }
  ],
  "permissions": [
    "storage"
  ],
  "applications": {
    "gecko": {
      "id": "amazontagger@doriangrey11.com"
    }
  }
}