Examine source code of Base64 decoder

{
  "update_url": "https://clients2.google.com/service/update2/crx",
  "name": "Base64 decoder",
  "version": "1.2",
  "description": "Decode Base64 string in omnibox",
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "omnibox": {
    "keyword": "base"
  },
  "manifest_version": 2
}