SQL Server blocking report with waitresource Database
The MSDN sys.dm_tran_locks documentation shows a list of resource and resource subtypes, including those affecting database locking:

BULKOP_BACKUP_DB         Database backups with bulk operations.
BULKOP_BACKUP_LOG        Database log backups with bulk operations.
CHANGE_TRACKING_CLEANUP  Change tracking cleanup tasks.
CT_DDL                   Database and table-level change tracking DDL operations.
CONVERSATION_PRIORITY    Service Broker conversation priority operations such
                             as CREATE BROKER PRIORITY.
DDL                      Data definition language (DDL) operations with 
                             filegroup operations, such as drop.
ENCRYPTION_SCAN          TDE encryption synchronization.
PLANGUIDE                Plan guide synchronization.
RESOURCE_GOVERNOR_DDL    DDL operations for resource governor operations such 
                             as ALTER RESOURCE POOL.
SHRINK                   Database shrink operations.
STARTUP                  Used for database startup synchronization.