Examine source code of Always Twitter Mobile

{
  "background": {
    "persistent": true,
    "scripts": [
      "background.js"
    ]
  },
  "description": "Ensure all visits to Twitter are to mobile.twitter.com",
  "homepage_url": "https://github.com/nikcorg/always-twitter-mobile",
  "manifest_version": 2,
  "name": "Always Twitter Mobile",
  "permissions": [
    "*://www.twitter.com/*",
    "*://twitter.com/*",
    "webRequest",
    "webRequestBlocking"
  ],
  "version": "1.10",
  "browser_specific_settings": {
    "gecko": {
      "id": "{d41fbc45-e41a-4f27-8031-1a98f3160f75}"
    }
  }
}