Examine source code of start

{
  "name": "start",
  "description": "replaces the new tab page with simple hackernews",
  "icons": {
    "128": "icon.png"
  },
  "manifest_version": 2,
  "version": "1.4",
  "chrome_url_overrides": {
    "newtab": "index.html"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "start@stehlik.me"
    }
  }
}