This removes the hardcoded value of `collate_by_trajectory` in the cloud
map builder server and permits to configure `collate_by_trajectory`
option with lua.
This allows Cartographer to use normal Application Default Credentials
(ADC) instead of a hand-generated format.
Google-internally, we'll only use ADC going forward. At your option, I
can keep the old code for the token files around if you think it would
be generally useful. Many OSS programs follow the same approach.
damienrg
Steve Wolter
Christoph Schütte
Alexander Belyaev
gaschler