code: func (c *Emulation) SetVisibleSize(width int, height int) (*gcdmessage.ChromeResponse, error) {
  	var v EmulationSetVisibleSizeParams
  	v.Width = width
  	v.Height = height
  	return c.SetVisibleSizeWithParams(&v)
  }
docs: // SetVisibleSize - Resizes the frame/viewport of the page. Note that this does not affect the frame's container (e.g. browser window). Can be used to produce screenshots of the specified size. Not supported on Android.
  // width - Frame width (DIP).
  // height - Frame height (DIP).