Examine source code of Gradient New Tab

{
  "manifest_version": 2,
  "name": "Gradient New Tab",
  "description": "This extension displays a colorful gradient on the page that appears when opening a new tab.",
  "version": "0.1.2",
  "icons": {
    "128": "icon128.png"
  },
  "chrome_url_overrides": {
    "newtab": "index.html"
  }
}