Examine source code of CopyURL

{
  "manifest_version": 2,
  "name": "CopyURL",
  "version": "1.0.1",
  "description": "Generate a floating button write the current URL to clipboard once clicked.",
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "copyurl.js"
      ],
      "css": [
        "css/styles.css"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{852013b6-3c2b-4f20-b4da-f0a18224c0f7}"
    }
  }
}