Examine source code of Extended Degiro summary

{
  "name": "Extended Degiro summary",
  "description": "Displays some missing account data on Degiro dashboard.",
  "version": "3",
  "manifest_version": 2,
  "permissions": [
    "tabs",
    "https://trader.degiro.nl/*"
  ],
  "content_scripts": [
    {
      "matches": [
        "https://trader.degiro.nl/*"
      ],
      "js": [
        "contentscript.js"
      ]
    }
  ],
  "icons": {
    "16": "icon.png",
    "128": "icon-128.png",
    "246": "icon-246.jpg"
  }
}