Examine source code of Amazon Theme

{
  "manifest_version": 2,
  "name": "Amazon Theme",
  "version": "1.0",
  "description": "Adds minimal themes to many websites.",
  "icons": {
    "48": "icon.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.amazon.com/*",
        "*://*.amazon.co.uk/*",
        "*://*.amazon.fr/*",
        "*://*.amazon.ca/*",
        "*://*.amazon.com.mx/*",
        "*://*.amazon.de/*",
        "*://*.amazon.es/*",
        "*://*.amazon.it/*",
        "*://*.amazon.co.jp/*",
        "*://*.amazon.in/*",
        "*://*.amazon.com.au/*",
        "*://*.amazon.cn/*"
      ],
      "js": [
        "theme.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{397fde7c-4469-4789-92c9-74dec778e669}"
    }
  }
}