Examine source code of Block WhatsApp Shortcuts

{
  "manifest_version": 2,
  "name": "Block WhatsApp Shortcuts",
  "version": "1.0",
  "browser_specific_settings": {
    "gecko": {
      "id": "block-whatsapp-shortcuts@josesanmartin.net",
      "strict_min_version": "58.0"
    }
  },
  "description": "Blocks Ctrl+Del shortcut in WhatsApp web.",
  "icons": {
    "48": "icons/icon-48.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://web.whatsapp.com/*"
      ],
      "js": [
        "block-whatsapp-shortcuts.js"
      ],
      "run_at": "document_start"
    }
  ]
}