Examine source code of Hide Scrollbar

{
  "manifest_version": 2,
  "name": "Hide Scrollbar",
  "version": "0.1.0",
  "description": "Hide webpage scrollbar.",
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "main.js"
      ]
    }
  ],
  "applications": {
    "gecko": {
      "id": "hidescrollbar@jokenngo"
    }
  }
}