Feature Request: Include blob size in GetApproximateSizes API

I would like to use the `GetApproximateSizes` API to determine the size of some non-overlapping discrete key ranges in a column family, but I noticed while testing that this doesn't include the size of blobs when using blobdb (correct me if I'm wrong here). Is it possible to add this, or some other way to get the information I'm looking for? TIA!