Examine source code of Link Preview Hover

{
  "manifest_version": 2,
  "name": "Link Preview Hover",
  "version": "1.0",
  "description": "Preview a website when hovering over a link.",
  "icons": {
    "48": "icon.png"
  },
  "permissions": [
    "activeTab"
  ],
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content_script.js"
      ],
      "css": [
        "style.css"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{1fa8de63-823f-4da6-8dd2-b1426a14422b}"
    }
  }
}