Examine source code of Hover Scroll Circles

{
  "manifest_version": 2,
  "name": "Hover Scroll Circles",
  "version": "1.1",
  "description": "Scroll pages by hovering over circular zones.",
  "permissions": [
    "activeTab"
  ],
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ],
      "css": [
        "style.css"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{39622d43-f08b-4d2c-9d3d-9b0959c2a8ed}"
    }
  }
}