It's not the same protocol as in virtualbox, though.
https://wiki.osdev.org/VirtualBox_Guest_Additions#Mouse_Inte...
https://wiki.osdev.org/VirtualBox_Guest_Additions#Mouse_Inte...
What they dropped is the older Chromium/VMGL-based protocol for 3D acceleration , in favor of VMware's solution (which has at least one working open-source guest-side linux driver); but nothing else (and as far as I can see nothing from that page, so it's not really outdated).