UserAgent: Mozilla/5.0 (X11; Fedora; Linux x86_64; rv:44.0) Gecko/20100101 Firefox/44.0

Steps to reproduce the problem:
1. open chrome in app mode, e.g. execute "google-chrome --app=http://xkcd.com"

What is the expected behavior?
The opened page's favicon is used as application window icon.

What went wrong?
The stock chrome icon is used in as application window icon.

Did this work before? Yes seeing many fixed bugs on the issue, for instance https://bugs.chromium.org/p/chromium/issues/detail?id=86908

Chrome version: Version 48.0.2564.116 (64-bit)  Channel: stable
OS Version: fedora 23
Flash Version: 

many such bugs are marked as duplicate, saying the feature works when you create an application from the chrome menus, but this bug is specifically about using the "--app" command-line option. I looked at many closed bugs, hope I didn't miss an open one...