Examine source code of Cutout Focus

{
  "manifest_version": 2,
  "name": "Cutout Focus",
  "version": "1.0",
  "description": "Blur entire image except for a circular area around the cursor to create a spotlight effect.",
  "permissions": [
    "<all_urls>"
  ],
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ],
      "css": [
        "style.css"
      ],
      "run_at": "document_idle"
    }
  ],
  "icons": {
    "48": "icon.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{cd7f327c-e864-4b1c-a3a1-88d7ab7253bf}"
    }
  }
}