The extension ID is literally hard coded in the code of the scheme hiding code. https://source.chromium.org/chromium/chromium/src/+/master:c...

How a proprietary extension can get preferential features illustrates that chromium is open source in name only.

Hardly. If you look at firefox's source, you will find several extensions that are hard-coded for special handling. This is not new.

True, but the distance between Firefox source and Firefox is config+compile.

You cannot compile Chrome. I've heard that Chromium can be compiled and run, but I've never actually seen it, or hear of anyone using that professionally.

I'm not sure what your point is... You thought it was weird that an extension would get preferential treatment, and I pointed out that this is true for Firefox also.

My point is that you are correct.

There are other factors at play which mitigate the preferential treatment, but it's definitely there in Firefox as well.

I looked into it several months ago and it looks like that extension is whitelisted to do it. If you try to repack the crx file and install it, the address bar doesn't get changed.