I bought the ChromeCast @ 6 months ago and never attempted to set it up on our downstairs A/V setup. In the upstairs BR we have a Roku and use NetFlix a lot.
With the downstairs setup, everything runs through the Onkyo 606 A/V receiver. The TV is a multi-HDMI port Pioneer Plasma with no internet capability. Running thru the Onkyo is a Panasonic Bluray, an XBox360, and the Pioneer. HDMI 1 is the Bluray, HDMI 3 is the Cox Cable box, HDMI 4 is the XBox, and HDMI 2 is free.
I have no idea whether to plug the Chromecast into the TV directly or to an HDMI on the Onkyo. Wife's phone is an Android Samsung S3.