Examine source code of Instant Image Zoom Pro

{
  "manifest_version": 2,
  "name": "Instant Image Zoom Pro",
  "version": "1.0",
  "description": "Enlarge images instantly when you hover over them.",
  "icons": {
    "64": "icon64.png",
    "128": "icon128.png"
  },
  "permissions": [
    "activeTab"
  ],
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{8b474ba6-f0a1-4b7d-a46c-05a9b8d7e208}",
      "strict_min_version": "113.0"
    }
  }
}