Examine source code of Portal

{
  "manifest_version": 2,
  "name": "Portal",
  "version": "1.0.0",
  "description": "Embed live websites in New Tab",
  "icons": {
    "16": "icons/icon-16.png",
    "32": "icons/icon-32.png",
    "48": "icons/icon-48.png",
    "96": "icons/icon-96.png",
    "128": "icons/icon-128.png",
    "256": "icons/icon-256.png"
  },
  "browser_action": {
    "default_title": "Open Portal"
  },
  "background": {
    "scripts": [
      "worker.js"
    ]
  },
  "content_scripts": [
    {
      "js": [
        "./contents/index.js"
      ],
      "matches": [
        "<all_urls>"
      ],
      "run_at": "document_idle",
      "all_frames": true
    }
  ],
  "chrome_url_overrides": {
    "newtab": "home.html"
  },
  "permissions": [
    "history",
    "declarativeNetRequest",
    "<all_urls>"
  ],
  "web_accessible_resources": [
    "public/*"
  ],
  "content_security_policy": " frame-src * ; style-src 'unsafe-inline' 'self' ; default-src 'self' ;",
  "browser_specific_settings": {
    "gecko": {
      "id": "{5a13f171-5111-43eb-ba5b-ebabf29e7359}"
    }
  }
}