Examine source code of Better UIs

{
  "manifest_version": 2,
  "name": "Better UIs",
  "version": "0.2",
  "description": "Redirects sites with awful and/or slow UIs (like medium.com) to sites with fast, lightweight UIs (like scribe.rip).",
  "icons": {
    "48": "icon-48.png"
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "permissions": [
    "webRequest",
    "webRequestBlocking",
    "<all_urls>",
    "storage"
  ],
  "options_ui": {
    "page": "options.html",
    "browser_style": true
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "better-uis@ameyama.com"
    }
  },
  "content_security_policy": "script-src 'self' 'unsafe-eval'; object-src 'self';"
}