Examine source code of Undirect

{
  "manifest_version": 2,
  "name": "Undirect",
  "version": "1.0",
  "description": "Tiny script that bypasses those annoying middleman webpages, taking you directly to the desired webpage.  Currently only functional for redirects through bluemediafiles.com, more to come.",
  "icons": {
    "48": "icon/icon.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.bluemediafiles.com/*"
      ],
      "js": [
        "undirect.js"
      ]
    }
  ]
}