Examine source code of Metro Start

{
  "name": "Metro Start",
  "short_name": "Metro Start",
  "version": "11.0.4",
  "manifest_version": 2,
  "description": "A new tab page for Google Chrome inspired by Zune",
  "chrome_url_overrides": {
    "newtab": "start.html"
  },
  "icons": {
    "16": "icons/icon16.png",
    "32": "icons/icon32.png",
    "128": "icons/icon128.png"
  },
  "permissions": [
    "storage",
    "https://api.metro-start.com/*"
  ],
  "optional_permissions": [
    "management",
    "bookmarks",
    "sessions",
    "tabs"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "metro-start@metro-start.com",
      "strict_min_version": "77.0"
    }
  }
}