Examine source code of SmoothScroll-plus

{
  "background": {
    "scripts": [
      "pages/background.js"
    ],
    "persistent": false
  },
  "content_scripts": [
    {
      "all_frames": true,
      "js": [
        "src/sscr.js",
        "src/middlemouse.js"
      ],
      "matches": [
        "http://*/*",
        "https://*/*",
        "ftp://*/*"
      ],
      "exclude_globs": [
        "*.pdf*"
      ],
      "run_at": "document_start"
    }
  ],
  "description": "Scroll smoothly on all websites with your mouse and keyboard.",
  "icons": {
    "16": "img/16n.png",
    "32": "img/32n.png",
    "48": "img/48n.png",
    "128": "img/128n.png"
  },
  "key": "MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQD1YCUodXSIZuDNa4PJGDCzSWnJAsPymJLQNj+fbxNHbE8BJ4x062dCB0rg0ovXXjNjGJW5FUX+aIEdhh1oNpouWkfu0GP6D6VXCrArXS1hKa7mV8jrBSuMLQo/aU3X7iieqkDzeSFRwUaAEp54C62J22sJ06EHI1QMLuCJ6C9lVQIDAQAB",
  "name": "SmoothScroll",
  "options_page": "pages/options.html",
  "version": "1.5.10",
  "manifest_version": 2,
  "permissions": [
    "storage",
    "http://*/*",
    "https://*/*"
  ],
  "web_accessible_resources": [
    "img/cursor.png"
  ]
}