Google Chromecast extension for Chrome has some settings hidden. The extension hides some debugging options under a small CSS “hidden” flag.

umer936 who found this and shared on XDA forums explains:

I found some extra settings on the Chromecast extension for Chrome. 

So I went to my Chrome extensions window and clicked “Options” for the Google Cast extension. 
In the tab, I right-clicked > Inspect Element. 

I noticed that a section of the page had a “display: none;” so I removed that and got this: 

These settings come with a warning that these may bring in unintended consequences and asks us to be careful before playing with them.

I am sure these will be useful for developers who are building apps for the latest Google hardware venture.