tree ea39a94bc415e21930b0b7b06cefdacd315bf640
parent e3b49ef297e317f28c9146c6b12ffa89503367a6
author Ross Wang <rosswang@google.com> 1460763979 -0700
committer Ross Wang <rosswang@google.com> 1461117686 -0700

TBR: Renaming FirebaseSingleton -> persistence/FirebasePersistence

This is in preparation for factoring out persistence to enable Syncbase
persistence. Also adds a SyncbasePersistence stub class.

Change-Id: I96ef7913eb60dff277e48f0aee7c1cadda02a036