chromium/chrome/test/data/extensions/startup_pages/manifest.json

{
  "name": "chrome.extension.settings_override",
  "version": "0.1",
  "manifest_version": 2,
  "description": "end-to-end browser test for chrome.settings_override API",
  "chrome_settings_overrides": {
    "startup_pages": ["http://www.example.com/?param=__PARAM__"]
   }
}