Use a two-part data format version in IndexedDB metadata.

content/common/indexed_db/indexed_db.typemap

Index: content/common/indexed_db/indexed_db.typemap
diff --git a/content/common/indexed_db/indexed_db.typemap b/content/common/indexed_db/indexed_db.typemap
index 1640ff07cae988b08ba075654e0e2357cd9026b6..8144075458ef0d18c669623f86064c80afec4506 100644
--- a/content/common/indexed_db/indexed_db.typemap
+++ b/content/common/indexed_db/indexed_db.typemap
@@ -4,6 +4,7 @@
 
 mojom = "//content/common/indexed_db/indexed_db.mojom"
 public_headers = [
+  "//content/common/indexed_db/indexed_db_data_format_version.h",
   "//content/common/indexed_db/indexed_db_key.h",
   "//content/common/indexed_db/indexed_db_key_path.h",
   "//content/common/indexed_db/indexed_db_key_range.h",
@@ -14,6 +15,7 @@ traits_headers = [ "//content/common/indexed_db/indexed_db_struct_traits.h" ]
 type_mappings = [
   "indexed_db.mojom.CursorDirection=blink::WebIDBCursorDirection",
   "indexed_db.mojom.DatabaseMetadata=content::IndexedDBDatabaseMetadata",
+  "indexed_db.mojom.DataFormatVersion=content::IndexedDBDataFormatVersion",
   "indexed_db.mojom.DataLoss=blink::WebIDBDataLoss",
   "indexed_db.mojom.IndexKeys=content::IndexedDBIndexKeys",
   "indexed_db.mojom.IndexMetadata=content::IndexedDBIndexMetadata",