Examine source code of facebook-airplane-mode

{
  "manifest_version": 2,
  "name": "facebook-airplane-mode",
  "version": "1.1",
  "description": "Set facebook in airplane mode",
  "homepage_url": "https://github.com/amsdamsgram/facebook-airplane-mode",
  "icons": {
    "32": "icons/logo-32.png",
    "48": "icons/logo-48.png",
    "96": "icons/logo-96.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.facebook.com/",
        "https://*.facebook.com/?ref=logo"
      ],
      "js": [
        "airplane-mode.js"
      ],
      "css": [
        "airplane-mode.css"
      ],
      "run_at": "document_start"
    }
  ]
}