Examine source code of doublespace

{
  "manifest_version": 2,
  "name": "doublespace",
  "version": "0.1",
  "description": "Adds  a  second  space  between  each  word  -  might  help  people  with  dyslexia",
  "icons": {
    "48": "icon-48.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*/*"
      ],
      "js": [
        "doublespace.js"
      ]
    }
  ]
}