Examine source code of Force Old Reddit Design

{
  "manifest_version": 2,
  "name": "Old Reddit Design",
  "version": "1.0",
  "description": "Redirect any reddit.com url to old.reddit.com so the website is displayed in the older design.",
  "icons": {
    "48": "icons/reddit.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.reddit.com/*"
      ],
      "js": [
        "oldreddit.js"
      ],
      "run_at": "document_start"
    }
  ]
}