As of ubuntu 14.04 do this to put dropbox icon on menu bar :
sudo apt-get install nautilus-dropbox
You can start Dropbox from your applications menu.
UPDATE
issue this to view what Ubuntu package is involved
dpkg -l|grep dropbox
... output
ii dropbox 2015.10.28 amd64 cloud synchronization engine - CLI and Nautilus extension
so now dropbox package description gives mention of nautilus ... so lets view all files listed in that package ... issue
dpkg -L dropbox
sure enough it lists files which are nautilus related ... so to answer your comment - I would say the normal dropbox package does contain customizations for integration with nautilus so that stand along package nautilus-dropbox is no longer necessary