Description: We have an enumeration for the unknown QuotaClient which seems to be only used in unit tests.  This might have a purpose in how quota values are stored in the quota database. If this has no use outside of the unit tests, we should remove the enumeration.

https://cs.chromium.org/chromium/src/storage/browser/quota/quota_client.h?type=cs&sq=package:chromium&g=0&l=37