The latest build "39.0.2171.71" is not working with the middle mouse button to paste content, this is very annoying and I strongly think chromium should not alter such a system's default behavior.
Auto-assigned to maintainer chromium@FreeBSD.org
This bug should be closed. It's chromium's behavior by design and isn't even FBSD specific.
As amvandemore says, it is chromium-specific behavior.