Examine source code of ZapFácil

{
  "name": "ZapFácil",
  "version": "1.0.1",
  "description": "Envie mensagens no WhatsApp para qualquer número sem salvar na agenda.",
  "author": "Elvis Ferreira de Jesus",
  "permissions": [
    "tabs",
    "storage",
    "notifications"
  ],
  "background": {
    "scripts": [
      "src/js/background.js"
    ],
    "persistent": false
  },
  "browser_action": {
    "default_popup": "src/popup.html",
    "default_icon": "src/img/icon.png"
  },
  "manifest_version": 2,
  "browser_specific_settings": {
    "gecko": {
      "id": "zapfacil@elvis.me",
      "data_collection_permissions": {
        "required": [
          "none"
        ],
        "optional": []
      }
    }
  },
  "web_accessible_resources": [
    "src/help.html",
    "src/about.html",
    "src/img/pix_qr.jpg"
  ]
}