Examine source code of scroll-pgup_pgdn

{
  "manifest_version": 2,
  "name": "scroll-pg",
  "version": "1.11",
  "description": "Scroll page up/down on hovered element.",
  "browser_specific_settings": {
    "gecko": {
      "id": "{273aaa3e-fcce-462a-bd15-911e058710bd}"
    }
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "scroll.js"
      ]
    }
  ]
}