Examine source code of Productive Portal

{
  "manifest_version": 2,
  "name": "Productive Portal",
  "version": "0.1.5",
  "description": "Hourly planner to be productive",
  "icons": {
    "16": "icons/icon_16.png",
    "48": "icons/icon_48.png",
    "128": "icons/icon_128.png"
  },
  "chrome_url_overrides": {
    "newtab": "index.html"
  }
}