code: func (c *Page) StartScreencastWithParams(v *PageStartScreencastParams) (*gcdmessage.ChromeResponse, error) {
  	return gcdmessage.SendDefaultRequest(c.target, c.target.GetSendCh(), &gcdmessage.ParamRequest{Id: c.target.GetId(), Method: "Page.startScreencast", Params: v})
  }
docs: // StartScreencastWithParams - Starts sending each frame using the `screencastFrame` event.