Examine source code of Page Scroller

{
  "manifest_version": 2,
  "name": "Page Scroller",
  "version": "1.2.3resigned1",
  "description": "Page Scroller is an add-on that automatically scrolls down the webpage for you. Either you are reading some lyrics while playing an instrument, reading a book or an article, or just feeling too lazy to scroll down with your mouse, Page Scroller is the right tool for you!  It works on any website and it is super simple to use: after installing, visit any website and press '+', '-' (to move faster or slower) or ESC (to stop). You can even drag and drop the scroller box anywhere on the page you like (by dragging the header). Have fun! - pythones.gr",
  "icons": {
    "48": "icons/logo-48.png",
    "96": "icons/logo-96.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*/*"
      ],
      "js": [
        "scrollerAction.js"
      ],
      "css": [
        "scrollerStyle.css"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{a4b70302-942a-484b-a776-41c5c9104008}"
    }
  }
}