Update - Here is how I worked around this:
apt-get update
apt-get install -y libgbm-dev
apt-get install -y libxkbcommon-x11-0
apt-get install -y libgtk-3-0
Then I found that chrome headless won't run if you build as root - with
the following error.
[INFO] 18 05 2021 13:00:05.883:ERROR [launcher]: Cannot start ChromeHeadless
[INFO] [0518/130005.862638:ERROR:zygote_host_impl_linux.cc(90)] Running
as root without --no-sandbox is not supported. See
https://crbug.com/638180.
But compiling not as root - worked. Whew.
Just sharing in case this is not what we intended.
/Chuck