Examine source code of Life in Weeks

{
  "manifest_version": 2,
  "name": "Life in Weeks",
  "version": "1.3",
  "description": "Visualize your life in weeks on the new tab page",
  "icons": {
    "48": "icon.png"
  },
  "permissions": [
    "storage"
  ],
  "chrome_url_overrides": {
    "newtab": "new-tab.html"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{d8e9af6a-9ab5-4a0e-9e8c-c786dc5a2c2d}"
    }
  }
}