Examine source code of Link Preview Enhancer

{
  "manifest_version": 2,
  "name": "Link Preview Enhancer",
  "version": "1.0",
  "description": "Show link previews (meta descriptions or thumbnails) when hovering over links.",
  "permissions": [
    "activeTab",
    "<all_urls>"
  ],
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ],
      "css": [
        "content.css"
      ]
    }
  ],
  "icons": {
    "48": "icons/icon.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{31a59c22-8cef-42fc-923a-655013bc751e}"
    }
  }
}