Examine source code of Change New Tab

{
  "applications": {
    "gecko": {
      "id": "@newtabchange",
      "strict_min_version": "57.0"
    }
  },
  "manifest_version": 2,
  "name": "__MSG_extName__",
  "version": "1.9",
  "description": "__MSG_extDes__",
  "default_locale": "en",
  "chrome_url_overrides": {
    "newtab": "res/redirect.htm"
  },
  "icons": {
    "48": "res/icon.svg",
    "128": "res/icon.svg"
  },
  "background": {
    "scripts": [
      "res/background.js"
    ]
  },
  "options_ui": {
    "page": "res/options.htm",
    "open_in_tab": true,
    "browser_style": false
  },
  "permissions": [
    "storage"
  ]
}