Ref: http://kenfallon.com/finally-able-to-open-citrix-from-chrome/
Edit the file /usr/share/applications/wfica.desktop include the following:
[Desktop Entry]
Name=Citrix ICA client
GenericName=Citrix ICA Client
Comment=Citrix nFuse session file
Categories=Application
Encoding=UTF-8
Exec=/opt/Citrix/ICAClient/wfica
Icon=wfica
Terminal=false
Type=Application
MimeType=application/x-ica
Edit the file /usr/share/mime/packages/ica.xml include the following:
Citrix ICA launcher
And finally run the command
xdg-mime install --novendor /usr/share/mime/packages/ica.xml