Examine source code of GoodReadsButton

{
  "manifest_version": 2,
  "name": "GoodReadsButton",
  "version": "1.0",
  "description": "Adds a read button to all goodreads book pages.",
  "icons": {
    "48": "border-48.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.goodreads.com/*"
      ],
      "js": [
        "goodreads.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{b2609280-c640-4768-92b2-3e4d59eccad9}"
    }
  }
}