A previous change added these getters to CacheDataSource, but it can
also be useful to retrieve these components directly from the factory.
This is useful for tasks where we're going to need to build multiple
CacheDataSource instances (e.g., to make requests in parallel), and
also need to operate directly on the same components. It's a bit more
natural to retrieve them from the factory than from an arbitrary
CacheDataSource in this case, since it can avoid unnatural code where
you create a CacheDataSource instance earlier than you would otherwise
just to use its getters, and/or create one just to use its getters and
then throw it away.
PiperOrigin-RevId: 308606020
2e1024f0d1