The chromium package currently has generate-ninja in its Build-Depends:
list. I recently added cross build support to the package, and the lack
of a Multi-Arch: field on generate-ninja resulted in the dependency
needing a :native qualifier.

Helmut Grohne, at whose request I am filing this report, suggested that
a value of "foreign" is a good first approximation for this package's
M-A field, taking into account built-in variables like host_cpu.