Examine source code of Pixel Detective

{
  "manifest_version": 2,
  "name": "Pixel Detective",
  "version": "1.0",
  "description": "Mini game: shows a highly zoomed crop of an on-page image and challenges you to guess where it came from.",
  "icons": {},
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "pixel-detective.js"
      ],
      "run_at": "document_end"
    }
  ],
  "permissions": [
    "activeTab",
    "storage"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{d0fec0b6-cce7-4bc6-b035-ab93df3f8289}"
    }
  }
}