Examine source code of Custom New Tab Background

{
  "manifest_version": 2,
  "name": "Custom New Tab Background",
  "version": "1.0",
  "description": "Customize the background color of your new tab page.",
  "permissions": [
    "storage"
  ],
  "chrome_url_overrides": {
    "newtab": "newtab.html"
  },
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": {
      "48": "icons/icon.png"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{29d689af-b6fe-46d1-b4bd-50f86192369f}"
    }
  }
}