Examine source code of What CMS Is This

{
  "manifest_version": 2,
  "name": "What CMS Is This",
  "description": "Detect which CMS a site is using with the help of WhatCMS.org",
  "version": "0.2resigned1",
  "icons": {
    "38": "img/icon-38.png",
    "58": "img/icon-58.png",
    "76": "img/icon-76.png"
  },
  "permissions": [
    "activeTab",
    "tabs",
    "*://*/*"
  ],
  "browser_action": {
    "browser_style": true,
    "default_title": "Detect Content Management System",
    "default_popup": "pages/index.html",
    "default_icon": {
      "38": "img/icon-38.png",
      "58": "img/icon-58.png",
      "76": "img/icon-76.png"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{7be636bb-6095-4a4b-a977-2e2317c9e032}"
    }
  }
}