ippusb_bridge is a drop-in replacement for ippusbxd for Chrome OS. It provides support for connecting to IPP-over-USB printers, and forwarding arbitrary protocols (IPP, eSCL, etc.) to those printers via HTTP.
The impetus for creating this was that ippusbxd has lost a lot of interest since the release of ipp-usb, a similar project written in Golang. Upstream provides only some oversight, and the code is pure C and has security bugs.
Preferably, we would use ipp-usb on Chrome OS instead, but its binary size (~9MB) precludes it.
Thus, ippusb_bridge is the happy medium: written in a safe language, to avoid exposing unsafe code to all USB devices on the system, but still with a reasonable binary size.