Comment 1 for bug 1849478

In third_party/webrtc/webrtc.gni¹:

  # Set this to use PipeWire on the Wayland display server.
  # By default it's only enabled on desktop Linux (excludes ChromeOS) and
  # only when using the sysroot as PipeWire is not available in older and
  # supported Ubuntu and Debian distributions.
  rtc_use_pipewire = is_desktop_linux && use_sysroot

use_sysroot is set to false in snap builds, so rtc_use_pipewire would need to be explicitly set to true. This might require additional build/runtime deps (assuming they are available in Ubuntu 18.04, which is used to build the chromium snaps).

¹ https://cs.chromium.org/chromium/src/third_party/webrtc/webrtc.gni?type=cs&q=rtc_use_pipewire&sq=package:chromium&g=0&l=115