Examine source code of Spectrum Tab Page

{
  "manifest_version": 2,
  "name": "Spectrum Tab Page",
  "description": "A smooth, simple and colorful tab page.",
  "version": "3.0",
  "icons": {
    "48": "icon48.png",
    "128": "icon128.png",
    "256": "icon256.png"
  },
  "permissions": [
    "tabs"
  ],
  "chrome_url_overrides": {
    "newtab": "index.html"
  }
}