Examine source code of Just SERP Preview

{
  "manifest_version": 2,
  "name": "Just SERP Preview",
  "version": "1.0.0.0",
  "version_name": "1.0.0",
  "description": "SERP Preview Tool. Visualize how your site will appear on Google. Zero special permissions required. No signup. No ads. No tracking.",
  "author": "HeroTofu.com",
  "homepage_url": "https://herotofu.com/extensions/serp-preview",
  "background": {
    "scripts": [
      "service-worker-loader.js"
    ],
    "persistent": false
  },
  "browser_action": {
    "default_popup": "serp.html",
    "default_icon": {
      "16": "icons/16.png",
      "48": "icons/48.png",
      "128": "icons/128.png"
    }
  },
  "permissions": [
    "tabs",
    "contextMenus",
    "http://*/*",
    "https://*/*"
  ],
  "incognito": "split",
  "icons": {
    "16": "icons/16.png",
    "48": "icons/48.png",
    "128": "icons/128.png"
  },
  "web_accessible_resources": [
    "icons/16.png",
    "icons/48.png",
    "icons/128.png",
    "serp.html",
    "service-worker-loader.js"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{06563280-a6b5-45c9-b4c9-b92895198a4c}"
    }
  }
}