Examine source code of WikipediaMobilifier

{
  "manifest_version": 2,
  "name": "WikipediaMobilifier",
  "version": "1.0",
  "description": "Automatically redirects non-mobile Wikipedia pages to the mobile site.",
  "content_scripts": [
    {
      "matches": [
        "https://en.wikipedia.org/*"
      ],
      "js": [
        "wikipedia_mobilifier.js"
      ]
    }
  ]
}