Examine source code of CodeForces Magic

{
  "manifest_version": 2,
  "name": "CodeForces Magic",
  "description": "Do you think you must wait until Christmas to see your handle in GrandMaster color for a limited time? You are wrong! With this extension you can change your handle to any rank you want, even you can become one of CodeForces Headquarters!",
  "version": "1.0",
  "icons": {
    "48": "icons/icon48.png"
  },
  "content_scripts": [
    {
      "matches": [
        "http://codeforces.com/*",
        "https://codeforces.com/*"
      ],
      "js": [
        "content-script.js"
      ]
    }
  ],
  "permissions": [
    "storage",
    "tabs"
  ],
  "browser_action": {
    "default_icon": "icons/icon48.png",
    "default_title": "CodeForces Magic",
    "default_popup": "popup.html"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{f8554ef2-b722-4527-94ee-e72c9cae12b1}"
    }
  }
}