emulation/emulation.go
func (p SetDeviceMetricsOverrideParams) WithViewport(viewport *page.Viewport) *SetDeviceMetricsOverrideParams {
	p.Viewport = viewport
	return &p
}
func (p SetDeviceMetricsOverrideParams) WithViewport(viewport *page.Viewport) *SetDeviceMetricsOverrideParams {
	p.Viewport = viewport
	return &p
}
// WithViewport if set, the visible area of the page will be overridden to
// this viewport. This viewport change is not observed by the page, e.g.
// viewport-relative elements do not change positions.