Add most of the metadata-handling code for blobs. It's not quite all there, but

content/browser/indexed_db/indexed_db_leveldb_coding.cc

 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/indexed_db/indexed_db_leveldb_coding.h"
 
 #include <iterator>
 #include <limits>
 
 #include "base/logging.h"
@@ skipping 28 matching lines @@
 //
 // Global metadata
 // ---------------
 // The prefix is <0, 0, 0>, followed by a metadata type byte:
 //
 // <0, 0, 0, 0> => backing store schema version [SchemaVersionKey]
 // <0, 0, 0, 1> => maximum allocated database [MaxDatabaseIdKey]
 // <0, 0, 0, 2> => SerializedScriptValue version [DataVersionKey]
 // <0, 0, 0, 3>
 //   => Blob journal
-//     The format of the journal is: {database_id, blobKey}*.
+//     The format of the journal is:
+//         {database_id (var int), blobKey (var int)}*.
 //     If the blobKey is kAllBlobsKey, the whole database should be deleted.
 //     [BlobJournalKey]
 // <0, 0, 0, 4> => Live blob journal; same format. [LiveBlobJournalKey]
 // <0, 0, 0, 100, database id>
 //   => Existence implies the database id is in the free list
 //      [DatabaseFreeListKey]
 // <0, 0, 0, 201, origin, database name> => Database id [DatabaseNameKey]
 //
 //
 // Database metadata: [DatabaseMetaDataKey]
@@ skipping 1969 matching lines @@
 scoped_ptr<IndexedDBKey> IndexDataKey::primary_key() const {
   scoped_ptr<IndexedDBKey> key;
   StringPiece slice(encoded_primary_key_);
   if (!DecodeIDBKey(&slice, &key)) {
     // TODO(jsbell): Return error.
   }
   return key.Pass();
 }
 
 }  // namespace content