Examine source code of Image Grid Overlay

{
  "manifest_version": 2,
  "name": "Image Grid Overlay",
  "version": "1.0",
  "description": "Overlay a translucent grid on images for layout analysis.",
  "permissions": [
    "<all_urls>"
  ],
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "css": [
        "style.css"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_idle"
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{60bf129f-394f-4e17-8799-08d3657741ee}"
    }
  }
}