Examine source code of Concentrate: no surf

{
  "manifest_version": 2,
  "name": "Concentrate: don't let the internet rule you",
  "version": "1.0",
  "description": "Internet is distracting",
  "icons": {
    "512": "brain.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*/*"
      ],
      "js": [
        "index.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "t29otis480zx@gmail.com"
    }
  }
}