code: func (remote *RemoteDebugger) SetDeviceMetricsOverride(width int, height int, deviceScaleFactor float64, mobile bool, fitWindow bool) error {
  	_, err := remote.SendRequest("Emulation.setDeviceMetricsOverride", Params{
  		"width":             width,
  		"height":            height,
  		"deviceScaleFactor": deviceScaleFactor,
  		"mobile":            mobile,
  		"fitWindow":         fitWindow})
  
  	return err
  }
docs: // SetDeviceMetricsOverride sets mobile and fitWindow on top of device dimensions
  // Can be used to produce screenshots of mobile viewports.