Examine source code of Link Preview

{
  "manifest_version": 2,
  "name": "Link Preview",
  "version": "1.0",
  "description": "Shows a preview of the webpage when hovering over a link.",
  "permissions": [
    "activeTab"
  ],
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ],
      "css": [
        "popup.css"
      ]
    }
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{92f16ae3-50b2-40d4-aee4-a583dcd45f54}"
    }
  }
}