The workaround given in the upstream Chromium issue is to setup key bindings at the OS-level that are just noops.
$ mkdir -p ~/Library/KeyBindings
$ cat > ~/Library/KeyBindings/DefaultKeyBinding.dict <<EOF
{
"^@\UF701" = "noop";
"^@\UF702" = "noop";
"^@\UF703" = "noop";
}