Adding a schema file for handling DB downgrade. This schema file is part of the backup/restore set, and hence is available on a device with lower app version. Bug: 37257575 Change-Id: I69c8ef5f28d5209be6e6679412c7459d4eeda5d0
Bug: 28302573 Change-Id: If0889a3b00b88b134b19d7f790159dfafdcdb004