Examine source code of Web Messenger

{
  "manifest_version": 3,
  "version": "0.3.2",
  "name": "Web Messenger",
  "description": "Access to the WhatsApp official Web messenger in a standalone sandboxed window",
  "icons": {
    "16": "/data/icons/16.png",
    "32": "/data/icons/32.png",
    "48": "/data/icons/48.png",
    "64": "/data/icons/64.png",
    "128": "/data/icons/128.png",
    "256": "/data/icons/256.png"
  },
  "homepage_url": "https://add0n.com/whatsapp-messenger.html",
  "permissions": [
    "storage"
  ],
  "host_permissions": [
    "*://web.whatsapp.com/"
  ],
  "action": {},
  "content_scripts": [
    {
      "matches": [
        "*://web.whatsapp.com/"
      ],
      "js": [
        "/data/inject.js"
      ],
      "css": [
        "/data/inject.css"
      ],
      "all_frames": true,
      "run_at": "document_start",
      "world": "ISOLATED"
    },
    {
      "matches": [
        "*://web.whatsapp.com/"
      ],
      "js": [
        "/data/dom.js"
      ],
      "all_frames": true,
      "run_at": "document_start",
      "world": "MAIN"
    }
  ],
  "background": {
    "service_worker": "worker.js",
    "scripts": [
      "worker.js"
    ]
  },
  "web_accessible_resources": [
    {
      "resources": [
        "/data/window/home.svg",
        "/data/window/reload.svg",
        "/data/window/settings.svg"
      ],
      "matches": [
        "*://web.whatsapp.com/*"
      ]
    }
  ],
  "options_ui": {
    "page": "/data/options/index.html"
  },
  "commands": {
    "_execute_action": {}
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "rt42fsdty645jIidD@jetpack",
      "strict_min_version": "128.0"
    }
  }
}