Examine source code of HandChat

{
  "manifest_version": 2,
  "name": "HandChat",
  "description": "HandChat",
  "version": "0.0.3.0",
  "author": "HandChat",
  "icons": {
    "16": "assets/images/16x16.png",
    "32": "assets/images/32x32.png",
    "48": "assets/images/48x48.png",
    "128": "assets/images/128x128.png"
  },
  "browser_action": {
    "default_icon": {
      "16": "assets/images/16x16.png",
      "32": "assets/images/32x32.png",
      "48": "assets/images/48x48.png",
      "128": "assets/images/128x128.png"
    },
    "default_title": "HandChat"
  },
  "content_scripts": [
    {
      "matches": [
        "https://apiexpress.hand.chat/*"
      ],
      "js": [
        "updateChecker.js"
      ]
    },
    {
      "matches": [
        "https://web.whatsapp.com/*"
      ],
      "js": [
        "appendAssets.js",
        "fetchWebsocket.js"
      ]
    }
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "web_accessible_resources": [
    "eventListener.js",
    "assets/js/jquery.min.js",
    "assets/js/bootstrap.bundle.min.js",
    "assets/js/sweetAlert.js",
    "assets/js/dragula.js",
    "assets/js/dom-autoscroller.js",
    "assets/js/chartjs.min.js",
    "assets/js/core.js",
    "assets/js/gridjs.production.min.js",
    "assets/css/mermaid.min.css",
    "assets/css/dragula.css",
    "assets/css/animate.min.css",
    "assets/css/bootstrap.min.css",
    "assets/css/core.css"
  ],
  "permissions": [
    "storage",
    "tabs",
    "*://*.whatsapp.com/*",
    "*://*.hand.chat/*"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{73a47fd8-9cb0-470c-8337-2dbc8703aa07}"
    }
  }
}