Examine source code of Startup Page

{
  "manifest_version": 2,
  "name": "Startup Page",
  "version": "1.2.1",
  "description": "A simple startup page, with DuckDuckGo as the default search engine.",
  "chrome_url_overrides": {
    "newtab": "index.html"
  },
  "chrome_settings_overrides": {
    "homepage": "index.html"
  },
  "icons": {
    "32": "icons/32.png",
    "48": "icons/48.png",
    "96": "icons/96.png",
    "128": "icons/128.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{0ff0853e-a2ce-4e1e-a323-b24b52adfa2a}"
    }
  }
}