IndexedDB: Move IDB Mojo file to Blink (part 3)

Part 3 in moving the IDB Mojo file from content/common/indexed_db/
to third_party/blink/public/mojom/indexeddb/indexeddb.mojom.  This is
the final IDB Mojo move CL in this series.

Since this moves all of the remaining Mojo types to the Blink IDB Mojo
file, this CL also removes the previous content/common/indexed_db/ Mojo
file and its typemap infrastructure.

This commit:
- Move all classes and structs in content/common/indexed_db/ to Blink
- Random cleanup: remove a "using" call in indexed_db_database.h

This commit converts Chromium to the following Mojom types:
- indexed_db.mojom.Callback -> blink.mojom.IDBCallback
- indexed_db.mojom.Cursor -> blink.mojom.IDBCursor
- indexed_db.mojom.Database -> blink.mojom.IDBDatabase
- indexed_db.mojom.DatabaseCallback -> blink.mojom.IDBDatabaseCallback
- indexed_db.mojom.DatabaseMetadata -> blink.mojom.IDBDatabaseMetadata
- indexed_db.mojom.Factory -> blink.mojom.IDBFactory
- indexed_db.mojom.IndexKeys -> blink.mojom.IDBIndexKeys
- indexed_db.mojom.IndexMetadata -> blink.mojom.IDBIndexMetadata
- indexed_db.mojom.KeyRange -> blink.mojom.IDBKeyRange
- indexed_db.mojom.ObjectStoreMetadata -> blink.mojom.IDBObjectStoreMetadata
- indexed_db.mojom.Observation -> blink.mojom.IDBObserveration
- indexed_db.mojom.ObserverChanges -> blink.mojom.IDBObserverChanges
- indexed_db.mojom.PutMode -> blink.mojom.IDBPutMode
- indexed_db.mojom.ReturnValue -> blink.mojom.IDBReturnValue
- indexed_db.mojom.Status -> blink.mojom.IDBStatus
- indexed_db.mojom.TaskType -> blink.mojom.IDBTaskType
- indexed_db.mojom.TransactionMode -> blink.mojom.IDBTransactionMode

Bug: 717812
Change-Id: Ic1fcfce6efe89c043ca5f5cf06a32477d48419d6
Reviewed-on: https://chromium-review.googlesource.com/1189134
Commit-Queue: Chase Phillips <cmp@chromium.org>
Reviewed-by: John Abd-El-Malek <jam@chromium.org>
Reviewed-by: Kinuko Yasuda <kinuko@chromium.org>
Reviewed-by: Reilly Grant <reillyg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#586817}
77 files changed