Examine source code of Link Previewer

{
  "manifest_version": 2,
  "name": "Link Previewer",
  "description": "Show a mini preview of the target page text when hovering over links",
  "version": "1.0",
  "icons": {
    "64": "icons/icon64.png",
    "128": "icons/icon128.png"
  },
  "permissions": [
    "tabs",
    "<all_urls>"
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_end"
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{b21a61ab-c16a-4c91-93a6-76934e6fea40}",
      "strict_min_version": "111.0"
    }
  }
}