Examine source code of OldRedditRedirect

{
  "manifest_version": 2,
  "name": "OldReddit",
  "version": "1.0.0",
  "description": "Redirects www.reddit.com to old.reddit.com.",
  "permissions": [
    "webRequest",
    "webRequestBlocking",
    "https://www.reddit.com/",
    "https://old.reddit.com/"
  ],
  "icons": {
    "48": "icons/icon48.png",
    "96": "icons/icon96.png"
  },
  "background": {
    "scripts": [
      "scripts/redirect.js"
    ]
  }
}