constructor(opts = {}) {
    super(opts)
    this._userPrefsFromPlugins = {}

    const defaults = {
      userPrefs: {}
    }

    this._opts = Object.assign(defaults, opts)
  }
Launch puppeteer with arbitrary user preferences.

The user defined preferences will be merged with preferences set by other plugins.
Plugins can add user preferences by exposing a data entry with the name `userPreferences`.

Overview:
https://chromium.googlesource.com/chromium/src/+/master/chrome/common/pref_names.cc

@param {Object} opts - Options
@param {Object} [opts.userPrefs={}] - An object containing the preferences.

@example
const puppeteer = require('puppeteer-extra')
puppeteer.use(require('puppeteer-extra-plugin-user-preferences')({userPrefs: {
  webkit: {
    webprefs: {
      default_font_size: 22
    }
  }
}}))
const browser = await puppeteer.launch()