Examine source code of Zandu Sync

{
  "manifest_version": 2,
  "version": "4.0.0.0",
  "name": "Zandu Sync",
  "short_name": "Zandu",
  "description": "Monitoramento de novos leads.",
  "icons": {
    "128": "icon.png"
  },
  "browser_action": {
    "default_icon": "icon.png",
    "default_popup": "popup.html"
  },
  "permissions": [
    "webNavigation",
    "activeTab",
    "tabs",
    "storage",
    "<all_urls>",
    "https://app.zandu.com.br/*",
    "https://beta.zandu.com.br/*",
    "http://localhost:3469/*"
  ],
  "background": {
    "scripts": [
      "script.js"
    ]
  },
  "content_scripts": [
    {
      "js": [
        "contentScript.js"
      ],
      "matches": [
        "https://app.zandu.com.br/*",
        "https://beta.zandu.com.br/*",
        "https://web.whatsapp.com/*",
        "http://localhost:3469/*"
      ]
    }
  ],
  "externally_connectable": {
    "matches": [
      "https://app.zandu.com.br/*",
      "https://beta.zandu.com.br/*",
      "http://localhost:3469/*"
    ]
  }
}