Examine source code of Robinhood Scroll

{
  "manifest_version": 2,
  "name": "Robinhood Scroll",
  "version": "1.2.1",
  "description": "Adds watchlist scrollbar for Robinhood.com.",
  "content_scripts": [
    {
      "matches": [
        "*://*.robinhood.com/*"
      ],
      "js": [
        "add-scroll.js"
      ]
    }
  ]
}