Thanks for the inquiry.
Can you please elaborate your inquiry? Roku and Google Chromecast are two separate devices.
With more information we will be able to assist you further.
I've been able to interface my Google Chromecast TV streaming device to the Roku Onn Sound Bar. The problem that I've encountered is that the wireless rear speakers are not active.
if you are asking if Roku devices are compatible with GoogleCast (ChromeCast) casting/mirroring protocol, the answer is no - Roku devices are Miracast and AirPlay2 and DIAL compatible.