Examine source code of New Tab Focus Reminder

{
  "manifest_version": 2,
  "name": "New Tab Focus Reminder",
  "version": "1.0",
  "description": "Replaces the new tab with a reminder to stay focused.",
  "chrome_url_overrides": {
    "newtab": "focus.html"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{b989db31-45d0-465c-aa35-f18a71e28a81}"
    }
  }
}