Examine source code of Site Killer

{
  "manifest_version": 2,
  "name": "Site Killer",
  "version": "2.1.1",
  "description": "Kill unwanted sites",
  "icons": {
    "128": "icon.png"
  },
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "browser_action": {
    "default_icon": {
      "128": "icon.png"
    },
    "default_popup": "popup.html"
  },
  "permissions": [
    "notifications",
    "tabs"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{a7726144-3bad-4b9a-9a4a-b003914f77cd}"
    }
  }
}