Examine source code of Custom New Tab URL

{
  "manifest_version": 2,
  "name": "Custom New Tab URL",
  "version": "1.3",
  "description": "Change the new tab URL to a custom one.",
  "permissions": [
    "tabs",
    "storage"
  ],
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": {
      "48": "icon.png"
    }
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "chrome_url_overrides": {
    "newtab": "custom-newtab.html"
  },
  "icons": {
    "48": "icon.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{fbcc78c8-c7e3-49ba-972c-51008ec12a33}"
    }
  }
}