The bug is in VirtualBox's Guest Additions, which probably badly translates 3D controls from applications like Chromium and delivers the weird black flickering garbage.
The solution is to simply replace the version of VirtualBox Guest Additions you're using. I found that VBoxGuestAdditions_5.0.10.iso worked fine. Insert the disk into the OS via VirtualBox and do the normal sudo ./VBoxLinuxAdditions.run. This will remove the existing broken version of Guest Additions and install the working replacement.