Google Chromecast normally is not able to accept directly streaming address. However, there is a nice and easy way to stream m3u8 links on Chromecast using an android phone/tablet with the TVS_player APP.
If you are streaming on computer the .m3u8 file and you want to watch it on TV using Chromecast, TVS_player is one of the best APP that is able to do it easily.
You need to have a free account on www.iptv-updated.com. After you can organize your country groups adding manually the channels with the .m3u8 links that you want OR search the Channel from the internal search engine.
You need to organize the channels only once. After you can access to the same configuration from all yours Android mobile devices using the TVS_player App.
You can start now to stream m3u8 links on Chromecast playing each link from channels or favorites tabs. Of course you need before to initialize the chromecast communication.
To initialize the chromecast communication you need to push the chromecast icon located on top right of the app. Afterword you need to select one of the chromecast device in your home.