Examine source code of Real-Time Image Mirror

{
  "manifest_version": 2,
  "name": "Real-Time Image Mirror",
  "version": "1.0",
  "description": "Mirror images horizontally on hover for quick symmetry check.",
  "permissions": [
    "<all_urls>"
  ],
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_idle"
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{ea21b47f-0e22-4fa8-84c8-877098f456fa}"
    }
  }
}