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

content/browser/indexed_db/indexed_db_backing_store.cc

Index: content/browser/indexed_db/indexed_db_backing_store.cc
diff --git a/content/browser/indexed_db/indexed_db_backing_store.cc b/content/browser/indexed_db/indexed_db_backing_store.cc
index 64e15457774ea87de1cf32ff808660ff7c85a7ea..44a8876c518c1dd18ce614300c3b658e421fe1ca 100644
--- a/content/browser/indexed_db/indexed_db_backing_store.cc
+++ b/content/browser/indexed_db/indexed_db_backing_store.cc
@@ -128,6 +128,8 @@ enum IndexedDBBackingStoreErrorSource {
   CLEAR_OBJECT_STORE,
   READ_BLOB_JOURNAL,
   DECODE_BLOB_JOURNAL,
+  GET_BLOB_KEY_GENERATOR_CURRENT_NUMBER,
+  GET_BLOB_INFO_FOR_RECORD,
   INTERNAL_ERROR_MAX,
 };
 
@@ -304,7 +306,8 @@ const char* IndexedDBBackingStore::Comparator::Name() const {
 // 0 - Initial version.
 // 1 - Adds UserIntVersion to DatabaseMetaData.
 // 2 - Adds DataVersion to to global metadata.
-static const int64 kLatestKnownSchemaVersion = 2;
+// 3 - Adds metadata needed for blob support.
+static const int64 kLatestKnownSchemaVersion = 3;
 WARN_UNUSED_RESULT static bool IsSchemaKnown(LevelDBDatabase* db, bool* known) {
   int64 db_schema_version = 0;
   bool found = false;
@@ -341,15 +344,16 @@ WARN_UNUSED_RESULT static bool IsSchemaKnown(LevelDBDatabase* db, bool* known) {
   return true;
 }
 
-WARN_UNUSED_RESULT static bool SetUpMetadata(
-    LevelDBDatabase* db,
-    const std::string& origin_identifier) {
+// TODO(ericu): Move this down into the member section of this file.  I'm
+// leaving it here for this CL as it's easier to see the diffs in place.
+WARN_UNUSED_RESULT bool IndexedDBBackingStore::SetUpMetadata() {
   const uint32 latest_known_data_version =
       blink::kSerializedScriptValueVersion;
   const std::string schema_version_key = SchemaVersionKey::Encode();
   const std::string data_version_key = DataVersionKey::Encode();
 
-  scoped_refptr<LevelDBTransaction> transaction = new LevelDBTransaction(db);
+  scoped_refptr<LevelDBTransaction> transaction =
+      new LevelDBTransaction(db_.get());
 
   int64 db_schema_version = 0;
   int64 db_data_version = 0;
@@ -366,6 +370,12 @@ WARN_UNUSED_RESULT static bool SetUpMetadata(
     PutInt(transaction.get(), schema_version_key, db_schema_version);
     db_data_version = latest_known_data_version;
     PutInt(transaction.get(), data_version_key, db_data_version);
+    // If a blob directory already exists for this database, blow it away.  It's
+    // leftover from a partially-purged previous generation of data.
+    if (!base::DeleteFile(blob_path_, true)) {
+      INTERNAL_WRITE_ERROR(SET_UP_METADATA);

[cmumford, 2014/05/06 18:33:11]

INTERNAL_READ_ERROR_UNTESTED

[ericu, 2014/05/06 20:07:42]

INTERNAL_WRITE_ERROR_UNTESTED?  Switched to that.

+      return false;
+    }
   } else {
     // Upgrade old backing store.
     DCHECK_LE(db_schema_version, kLatestKnownSchemaVersion);
@@ -373,10 +383,10 @@ WARN_UNUSED_RESULT static bool SetUpMetadata(
       db_schema_version = 1;
       PutInt(transaction.get(), schema_version_key, db_schema_version);
       const std::string start_key =
-          DatabaseNameKey::EncodeMinKeyForOrigin(origin_identifier);
+          DatabaseNameKey::EncodeMinKeyForOrigin(origin_identifier_);
       const std::string stop_key =
-          DatabaseNameKey::EncodeStopKeyForOrigin(origin_identifier);
-      scoped_ptr<LevelDBIterator> it = db->CreateIterator();
+          DatabaseNameKey::EncodeStopKeyForOrigin(origin_identifier_);
+      scoped_ptr<LevelDBIterator> it = db_->CreateIterator();
       for (s = it->Seek(start_key);
            s.ok() && it->IsValid() && CompareKeys(it->Key(), stop_key) < 0;
            s = it->Next()) {
@@ -404,6 +414,13 @@ WARN_UNUSED_RESULT static bool SetUpMetadata(
       db_data_version = blink::kSerializedScriptValueVersion;
       PutInt(transaction.get(), data_version_key, db_data_version);
     }
+    if (db_schema_version < 3) {
+      db_schema_version = 3;
+      if (!base::DeleteFile(blob_path_, true)) {
+        INTERNAL_WRITE_ERROR(SET_UP_METADATA);

[cmumford, 2014/05/06 18:33:11]

INTERNAL_READ_ERROR_UNTESTED

[ericu, 2014/05/06 20:07:42]

Same?

[cmumford, 2014/05/06 20:41:47]

Woops - my note was bad (READ vs. WRITE). But yes, we now only use the
*_UNTESTED version of the macros everywhere _unless_ we have a unit test that
hits that one line.

+        return false;
+      }
+    }
   }
 
   if (!s.ok()) {
@@ -480,6 +497,55 @@ class DefaultLevelDBFactory : public LevelDBFactory {
   }
 };
 
+static bool GetBlobKeyGeneratorCurrentNumber(
+    LevelDBTransaction* leveldb_transaction,
+    int64 database_id,
+    int64* blob_key_generator_current_number) {
+  const std::string key_gen_key = DatabaseMetaDataKey::Encode(
+      database_id, DatabaseMetaDataKey::BLOB_KEY_GENERATOR_CURRENT_NUMBER);
+
+  // Default to initial number if not found.
+  int64 cur_number = DatabaseMetaDataKey::kBlobKeyGeneratorInitialNumber;
+  std::string data;
+
+  bool found = false;
+  bool ok = leveldb_transaction->Get(key_gen_key, &data, &found).ok();
+  if (!ok) {
+    INTERNAL_READ_ERROR(GET_BLOB_KEY_GENERATOR_CURRENT_NUMBER);

[cmumford, 2014/05/06 18:33:11]

INTERNAL_READ_ERROR_UNTESTED

[ericu, 2014/05/06 20:07:42]

Done.

+    return false;
+  }
+  if (found) {
+    StringPiece slice(data);
+    if (!DecodeVarInt(&slice, &cur_number) || !slice.empty() ||
+        !DatabaseMetaDataKey::IsValidBlobKey(cur_number)) {
+      INTERNAL_READ_ERROR(GET_BLOB_KEY_GENERATOR_CURRENT_NUMBER);

[cmumford, 2014/05/06 18:33:11]

INTERNAL_READ_ERROR_UNTESTED

[ericu, 2014/05/06 20:07:42]

Done.

+      return false;
+    }
+  }
+  *blob_key_generator_current_number = cur_number;
+  return true;
+}
+
+static bool UpdateBlobKeyGeneratorCurrentNumber(
+    LevelDBTransaction* leveldb_transaction,
+    int64 database_id,
+    int64 blob_key_generator_current_number) {
+#ifndef NDEBUG
+  int64 old_number;
+  if (!GetBlobKeyGeneratorCurrentNumber(
+          leveldb_transaction, database_id, &old_number))
+    return false;
+  DCHECK_LT(old_number, blob_key_generator_current_number);
+#endif
+  DCHECK(
+      DatabaseMetaDataKey::IsValidBlobKey(blob_key_generator_current_number));
+  const std::string key = DatabaseMetaDataKey::Encode(
+      database_id, DatabaseMetaDataKey::BLOB_KEY_GENERATOR_CURRENT_NUMBER);
+
+  PutVarInt(leveldb_transaction, key, blob_key_generator_current_number);
+  return true;
+}
+
 // TODO(ericu): Error recovery. If we persistently can't read the
 // blob journal, the safe thing to do is to clear it and leak the blobs,
 // though that may be costly. Still, database/directory deletion should always
@@ -573,6 +639,64 @@ static leveldb::Status MergeDatabaseIntoLiveBlobJournal(
   return leveldb::Status::OK();
 }
 
+// Blob Data is encoded as a series of:
+//   { is_file [bool], key [int64 as varInt],
+//     type [string-with-length, may be empty],
+//     (for Blobs only) size [int64 as varInt]
+//     (for Files only) fileName [string-with-length]
+//   }
+// There is no length field; just read until you run out of data.
+static std::string EncodeBlobData(
+    const std::vector<IndexedDBBlobInfo*>& blob_info) {
+  std::string ret;
+  std::vector<IndexedDBBlobInfo*>::const_iterator iter;
+  for (iter = blob_info.begin(); iter != blob_info.end(); ++iter) {
+    const IndexedDBBlobInfo& info = **iter;
+    EncodeBool(info.is_file(), &ret);
+    EncodeVarInt(info.key(), &ret);
+    EncodeStringWithLength(info.type(), &ret);
+    if (info.is_file())
+      EncodeStringWithLength(info.file_name(), &ret);
+    else
+      EncodeVarInt(info.size(), &ret);

[jsbell, 2014/05/06 18:29:48]

Can you add '(var int') to the docs at the top of indexed_db_leveldb_coding.cc ?

[ericu, 2014/05/06 20:07:42]

Done.  That's the blob journal, not this blob data, though.
Since this is done here, not in that file, it's not documented over there, only
in the comment above this function.

+  }
+  return ret;
+}
+
+static bool DecodeBlobData(const std::string& data,
+                           std::vector<IndexedDBBlobInfo>* output) {
+  std::vector<IndexedDBBlobInfo> ret;
+  output->clear();
+  StringPiece slice(data);
+  while (!slice.empty()) {
+    bool is_file;
+    int64 key;
+    base::string16 type;
+    int64 size;
+    base::string16 file_name;
+
+    if (!DecodeBool(&slice, &is_file))
+      return false;
+    if (!DecodeVarInt(&slice, &key) ||
+        !DatabaseMetaDataKey::IsValidBlobKey(key))
+      return false;
+    if (!DecodeStringWithLength(&slice, &type))
+      return false;
+    if (is_file) {
+      if (!DecodeStringWithLength(&slice, &file_name))
+        return false;
+      ret.push_back(IndexedDBBlobInfo(key, type, file_name));
+    } else {
+      if (!DecodeVarInt(&slice, &size) || size < 0)
+        return false;
+      ret.push_back(IndexedDBBlobInfo(type, static_cast<uint64>(size), key));
+    }
+  }
+  output->swap(ret);
+
+  return true;
+}
+
 IndexedDBBackingStore::IndexedDBBackingStore(
     IndexedDBFactory* indexed_db_factory,
     const GURL& origin_url,
@@ -589,7 +713,8 @@ IndexedDBBackingStore::IndexedDBBackingStore(
       task_runner_(task_runner),
       db_(db.Pass()),
       comparator_(comparator.Pass()),
-      active_blob_registry_(this) {}
+      active_blob_registry_(this) {
+}
 
 IndexedDBBackingStore::~IndexedDBBackingStore() {
   if (!blob_path_.empty() && !child_process_ids_granted_.empty()) {
@@ -923,13 +1048,19 @@ scoped_refptr<IndexedDBBackingStore> IndexedDBBackingStore::Open(
     return scoped_refptr<IndexedDBBackingStore>();
   }
 
-  return Create(indexed_db_factory,
-                origin_url,
-                blob_path,
-                request_context,
-                db.Pass(),
-                comparator.Pass(),
-                task_runner);
+  scoped_refptr<IndexedDBBackingStore> backing_store =
+      Create(indexed_db_factory,
+             origin_url,
+             blob_path,
+             request_context,
+             db.Pass(),
+             comparator.Pass(),
+             task_runner);
+
+  if (clean_journal &&
+      !backing_store->CleanUpBlobJournal(LiveBlobJournalKey::Encode()).ok())

[cmumford, 2014/05/06 18:33:11]

If SetupMetaData fails for whatever reason backing_store will be NULL.

[ericu, 2014/05/06 20:07:42]

Fixed.

+    return scoped_refptr<IndexedDBBackingStore>();

[cmumford, 2014/05/06 18:33:11]

Do you want to record a histogram value here in case of failure?

[ericu, 2014/05/06 20:07:42]

Yeah, good idea.

+  return backing_store;
 }
 
 // static
@@ -986,8 +1117,7 @@ scoped_refptr<IndexedDBBackingStore> IndexedDBBackingStore::Create(
                                 db.Pass(),
                                 comparator.Pass(),
                                 task_runner));
-  if (!SetUpMetadata(backing_store->db_.get(),
-                     backing_store->origin_identifier_))
+  if (!backing_store->SetUpMetadata())
     return scoped_refptr<IndexedDBBackingStore>();
 
   return backing_store;
@@ -1084,6 +1214,29 @@ leveldb::Status IndexedDBBackingStore::GetIDBDatabaseMetaData(
     INTERNAL_READ_ERROR_UNTESTED(GET_IDBDATABASE_METADATA);
   }
 
+  // We don't cache this, we just check it if it's there.
+  int64 blob_key_generator_current_number =
+      DatabaseMetaDataKey::kInvalidBlobKey;
+
+  s = GetVarInt(
+      db_.get(),
+      DatabaseMetaDataKey::Encode(
+          metadata->id, DatabaseMetaDataKey::BLOB_KEY_GENERATOR_CURRENT_NUMBER),
+      &blob_key_generator_current_number,
+      found);
+  if (!s.ok()) {
+    INTERNAL_READ_ERROR(GET_IDBDATABASE_METADATA);

[cmumford, 2014/05/06 18:33:11]

_UNTESTED

[ericu, 2014/05/06 20:07:42]

Done.

+    return s;
+  }
+  if (!*found) {
+    // This database predates blob support.
+    *found = true;
+  } else if (!DatabaseMetaDataKey::IsValidBlobKey(
+                 blob_key_generator_current_number)) {
+    INTERNAL_CONSISTENCY_ERROR(GET_IDBDATABASE_METADATA);

[cmumford, 2014/05/06 18:33:11]

_UNTESTED

[ericu, 2014/05/06 20:07:42]

Done.

+    return InternalInconsistencyStatus();
+  }
+
   return s;
 }
 
@@ -1137,6 +1290,12 @@ leveldb::Status IndexedDBBackingStore::CreateIDBDatabaseMetaData(
             DatabaseMetaDataKey::Encode(*row_id,
                                         DatabaseMetaDataKey::USER_INT_VERSION),
             int_version);
+  PutVarInt(
+      transaction.get(),
+      DatabaseMetaDataKey::Encode(
+          *row_id, DatabaseMetaDataKey::BLOB_KEY_GENERATOR_CURRENT_NUMBER),
+      DatabaseMetaDataKey::kBlobKeyGeneratorInitialNumber);
+
   s = transaction->Commit();
   if (!s.ok())
     INTERNAL_WRITE_ERROR_UNTESTED(CREATE_IDBDATABASE_METADATA);
@@ -1169,15 +1328,47 @@ static leveldb::Status DeleteRange(LevelDBTransaction* transaction,
   return s;
 }
 
+static leveldb::Status DeleteBlobsInObjectStore(
+    IndexedDBBackingStore::Transaction* transaction,
+    int64 database_id,
+    int64 object_store_id) {
+  std::string start_key, end_key;
+  start_key =
+      BlobEntryKey::EncodeMinKeyForObjectStore(database_id, object_store_id);
+  end_key =
+      BlobEntryKey::EncodeStopKeyForObjectStore(database_id, object_store_id);
+
+  scoped_ptr<LevelDBIterator> it = transaction->transaction()->CreateIterator();
+  for (it->Seek(start_key);

[cmumford, 2014/05/06 18:33:11]

Seek/Next/etc. now return Status objects. should check these.

[ericu, 2014/05/06 20:07:42]

Working on that now.  On the last step of an iterator, to where it runs off the
end of the database, does it still return s.ok() even if !it->IsValid()?  I'm
crawling through the leveldb code, and it's not clear [and is AFAICT
undocumented].

[cmumford, 2014/05/06 20:41:47]

I believe that it will return OK() and the iterator will be !valid, but I'm not
100% on that. When I modified those routines to return status codes I left in
the IsValid() checks and added OK() checks to them and all tests still pass
(FWTW).

+       it->IsValid() && CompareKeys(it->Key(), end_key) < 0;
+       it->Next()) {
+    StringPiece key_piece(it->Key());
+    std::string user_key =
+        BlobEntryKey::ReencodeToObjectStoreDataKey(&key_piece);
+    if (!user_key.size()) {
+      INTERNAL_CONSISTENCY_ERROR(GET_IDBDATABASE_METADATA);

[cmumford, 2014/05/06 18:33:11]

_UNTESTED

[ericu, 2014/05/06 20:07:42]

Done.

+      return InternalInconsistencyStatus();
+    }
+    transaction->PutBlobInfo(
+        database_id, object_store_id, user_key, NULL, NULL);
+  }
+  return leveldb::Status::OK();
+}
+
 leveldb::Status IndexedDBBackingStore::DeleteDatabase(
     const base::string16& name) {
   IDB_TRACE("IndexedDBBackingStore::DeleteDatabase");
   scoped_ptr<LevelDBDirectTransaction> transaction =
       LevelDBDirectTransaction::Create(db_.get());
 
+  leveldb::Status s;
+  s = CleanUpBlobJournal(BlobJournalKey::Encode());
+  if (!s.ok())
+    return InternalInconsistencyStatus();

[cmumford, 2014/05/06 18:33:11]

Why not return "s" here?

[ericu, 2014/05/06 20:07:42]

Done.

+
   IndexedDBDatabaseMetadata metadata;
   bool success = false;
-  leveldb::Status s = GetIDBDatabaseMetaData(name, &metadata, &success);
+  s = GetIDBDatabaseMetaData(name, &metadata, &success);
   if (!s.ok())
     return s;
   if (!success)
@@ -1200,16 +1391,28 @@ leveldb::Status IndexedDBBackingStore::DeleteDatabase(
   const std::string key = DatabaseNameKey::Encode(origin_identifier_, name);
   transaction->Remove(key);
 
-  // TODO(ericu): Put the real calls to the blob journal code here.  For now,
-  // I've inserted fake calls so that we don't get "you didn't use this static
-  // function" compiler errors.
+  bool need_cleanup = false;
+  if (active_blob_registry()->MarkDeletedCheckIfUsed(
+          metadata.id, DatabaseMetaDataKey::kAllBlobsKey)) {
+    s = MergeDatabaseIntoLiveBlobJournal(transaction.get(), metadata.id);
+    if (!s.ok())
+      return s;
+  } else {
+    UpdateBlobJournalWithDatabase(transaction.get(), metadata.id);
+    need_cleanup = true;
+  }
+
+  // TODO(ericu): Remove these fake calls, added to avoid "defined but unused"
+  // compiler errors until the code that makes the real calls can be added.
   if (false) {
+    std::vector<IndexedDBBlobInfo*> fake;
+    EncodeBlobData(fake);
+
     scoped_refptr<LevelDBTransaction> fake_transaction =
         new LevelDBTransaction(NULL);
     BlobJournalType fake_journal;
-    MergeDatabaseIntoLiveBlobJournal(transaction.get(), metadata.id);
-    UpdateBlobJournalWithDatabase(transaction.get(), metadata.id);
     MergeBlobsIntoLiveBlobJournal(fake_transaction.get(), fake_journal);
+    UpdateBlobKeyGeneratorCurrentNumber(fake_transaction.get(), 0, 0);
   }
 
   s = transaction->Commit();
@@ -1217,6 +1420,10 @@ leveldb::Status IndexedDBBackingStore::DeleteDatabase(
     INTERNAL_WRITE_ERROR_UNTESTED(DELETE_DATABASE);
     return s;
   }
+
+  if (need_cleanup)
+    CleanUpBlobJournal(BlobJournalKey::Encode());
+
   db_->Compact(start_key, stop_key);
   return s;
 }
@@ -1525,6 +1732,12 @@ leveldb::Status IndexedDBBackingStore::DeleteObjectStore(
     return InternalInconsistencyStatus();
   }
 
+  s = DeleteBlobsInObjectStore(transaction, database_id, object_store_id);
+  if (!s.ok()) {
+    INTERNAL_CONSISTENCY_ERROR(DELETE_OBJECT_STORE);

[cmumford, 2014/05/06 18:33:11]

_UNTESTED

[ericu, 2014/05/06 20:07:42]

Done.

+    return s;
+  }
+
   s = DeleteRange(
       leveldb_transaction,
       ObjectStoreMetaDataKey::Encode(database_id, object_store_id, 0),
@@ -1593,7 +1806,7 @@ leveldb::Status IndexedDBBackingStore::GetRecord(
   }
 
   record->bits = slice.as_string();
-  return s;
+  return transaction->GetBlobInfoForRecord(database_id, leveldb_key, record);
 }
 
 WARN_UNUSED_RESULT static leveldb::Status GetNewVersionNumber(
@@ -1689,9 +1902,11 @@ leveldb::Status IndexedDBBackingStore::ClearObjectStore(
 
   leveldb::Status s =
       DeleteRange(transaction->transaction(), start_key, stop_key);
-  if (!s.ok())
+  if (!s.ok()) {
     INTERNAL_WRITE_ERROR(CLEAR_OBJECT_STORE);
-  return s;
+    return s;
+  }
+  return DeleteBlobsInObjectStore(transaction, database_id, object_store_id);
 }
 
 leveldb::Status IndexedDBBackingStore::DeleteRecord(
@@ -2289,6 +2504,68 @@ leveldb::Status IndexedDBBackingStore::CleanUpBlobJournal(
   return journal_transaction->Commit();
 }
 
+leveldb::Status IndexedDBBackingStore::Transaction::GetBlobInfoForRecord(
+    int64 database_id,
+    const std::string& object_store_data_key,
+    IndexedDBValue* value) {
+  BlobChangeRecord* change_record = NULL;
+  BlobChangeMap::const_iterator blob_iter =
+      blob_change_map_.find(object_store_data_key);
+  if (blob_iter != blob_change_map_.end())
+    change_record = blob_iter->second;
+  else {

[jsbell, 2014/05/06 18:29:48]

Inconsistent bracing (if any if/else branch uses braces, all must)

[ericu, 2014/05/06 20:07:42]

Done.

+    blob_iter = incognito_blob_map_.find(object_store_data_key);
+    if (blob_iter != incognito_blob_map_.end())
+      change_record = blob_iter->second;
+  }
+  if (change_record) {
+    // Either we haven't written the blob to disk yet or we're in incognito
+    // mode, so we have to send back the one they sent us.  This change record
+    // includes the original UUID.
+    value->blob_info = change_record->blob_info();
+    return leveldb::Status::OK();
+  }
+
+  BlobEntryKey blob_entry_key;
+  StringPiece leveldb_key_piece(object_store_data_key);
+  if (!BlobEntryKey::FromObjectStoreDataKey(&leveldb_key_piece,
+                                            &blob_entry_key)) {
+    NOTREACHED();
+    return InternalInconsistencyStatus();
+  }
+  scoped_ptr<LevelDBIterator> it = transaction()->CreateIterator();
+  std::string encoded_key = blob_entry_key.Encode();
+  it->Seek(encoded_key);

[cmumford, 2014/05/06 18:33:11]

Status

[ericu, 2014/05/06 20:07:42]

Done.

+  if (it->IsValid() && CompareKeys(it->Key(), encoded_key) == 0) {
+    if (!DecodeBlobData(it->Value().as_string(), &value->blob_info)) {
+      INTERNAL_READ_ERROR(GET_BLOB_INFO_FOR_RECORD);
+      return InternalInconsistencyStatus();
+    }
+    std::vector<IndexedDBBlobInfo>::iterator iter;
+    for (iter = value->blob_info.begin(); iter != value->blob_info.end();
+         ++iter) {
+      iter->set_file_path(
+          backing_store_->GetBlobFileName(database_id, iter->key()));
+      iter->set_mark_used_callback(
+          backing_store_->active_blob_registry()->GetAddBlobRefCallback(
+              database_id, iter->key()));
+      iter->set_release_callback(
+          backing_store_->active_blob_registry()->GetFinalReleaseCallback(
+              database_id, iter->key()));
+      if (iter->is_file()) {
+        base::File::Info info;
+        if (base::GetFileInfo(iter->file_path(), &info)) {
+          // This should always work, but it isn't fatal if it doesn't; it just
+          // means a potential slow synchronous call from the renderer later.
+          iter->set_last_modified(info.last_modified);
+          iter->set_size(info.size);
+        }
+      }
+    }
+  }
+  return leveldb::Status::OK();
+}
+
 void IndexedDBBackingStore::CleanPrimaryJournalIgnoreReturn() {
   CleanUpBlobJournal(BlobJournalKey::Encode());
 }
@@ -2612,11 +2889,13 @@ leveldb::Status IndexedDBBackingStore::KeyExistsInIndex(
 
 IndexedDBBackingStore::Cursor::Cursor(
     const IndexedDBBackingStore::Cursor* other)
-    : transaction_(other->transaction_),
+    : backing_store_(other->backing_store_),
+      transaction_(other->transaction_),
+      database_id_(other->database_id_),
       cursor_options_(other->cursor_options_),
       current_key_(new IndexedDBKey(*other->current_key_)) {
   if (other->iterator_) {
-    iterator_ = transaction_->CreateIterator();
+    iterator_ = transaction_->transaction()->CreateIterator();
 
     if (other->iterator_->IsValid()) {
       leveldb::Status s = iterator_->Seek(other->iterator_->Key());
@@ -2626,13 +2905,20 @@ IndexedDBBackingStore::Cursor::Cursor(
   }
 }
 
-IndexedDBBackingStore::Cursor::Cursor(LevelDBTransaction* transaction,
-                                      const CursorOptions& cursor_options)
-    : transaction_(transaction), cursor_options_(cursor_options) {}
+IndexedDBBackingStore::Cursor::Cursor(
+    scoped_refptr<IndexedDBBackingStore> backing_store,
+    IndexedDBBackingStore::Transaction* transaction,
+    int64 database_id,
+    const CursorOptions& cursor_options)
+    : backing_store_(backing_store),
+      transaction_(transaction),
+      database_id_(database_id),
+      cursor_options_(cursor_options) {
+}
 IndexedDBBackingStore::Cursor::~Cursor() {}
 
 bool IndexedDBBackingStore::Cursor::FirstSeek(leveldb::Status* s) {
-  iterator_ = transaction_->CreateIterator();
+  iterator_ = transaction_->transaction()->CreateIterator();
   if (cursor_options_.forward)
     *s = iterator_->Seek(cursor_options_.low_key);
   else
@@ -2815,9 +3101,14 @@ IndexedDBBackingStore::Cursor::record_identifier() const {
 class ObjectStoreKeyCursorImpl : public IndexedDBBackingStore::Cursor {
  public:
   ObjectStoreKeyCursorImpl(
-      LevelDBTransaction* transaction,
+      scoped_refptr<IndexedDBBackingStore> backing_store,
+      IndexedDBBackingStore::Transaction* transaction,
+      int64 database_id,
       const IndexedDBBackingStore::Cursor::CursorOptions& cursor_options)
-      : IndexedDBBackingStore::Cursor(transaction, cursor_options) {}
+      : IndexedDBBackingStore::Cursor(backing_store,
+                                      transaction,
+                                      database_id,
+                                      cursor_options) {}
 
   virtual Cursor* Clone() OVERRIDE {
     return new ObjectStoreKeyCursorImpl(this);
@@ -2874,9 +3165,14 @@ bool ObjectStoreKeyCursorImpl::LoadCurrentRow() {
 class ObjectStoreCursorImpl : public IndexedDBBackingStore::Cursor {
  public:
   ObjectStoreCursorImpl(
-      LevelDBTransaction* transaction,
+      scoped_refptr<IndexedDBBackingStore> backing_store,
+      IndexedDBBackingStore::Transaction* transaction,
+      int64 database_id,
       const IndexedDBBackingStore::Cursor::CursorOptions& cursor_options)
-      : IndexedDBBackingStore::Cursor(transaction, cursor_options) {}
+      : IndexedDBBackingStore::Cursor(backing_store,
+                                      transaction,
+                                      database_id,
+                                      cursor_options) {}
 
   virtual Cursor* Clone() OVERRIDE { return new ObjectStoreCursorImpl(this); }
 
@@ -2925,6 +3221,11 @@ bool ObjectStoreCursorImpl::LoadCurrentRow() {
   EncodeIDBKey(*current_key_, &encoded_key);
   record_identifier_.Reset(encoded_key, version);
 
+  if (!transaction_->GetBlobInfoForRecord(database_id_,
+                                          iterator_->Key().as_string(),
+                                          &current_value_).ok()) {
+    return false;
+  }
   current_value_.bits = value_slice.as_string();
   return true;
 }
@@ -2932,9 +3233,14 @@ bool ObjectStoreCursorImpl::LoadCurrentRow() {
 class IndexKeyCursorImpl : public IndexedDBBackingStore::Cursor {
  public:
   IndexKeyCursorImpl(
-      LevelDBTransaction* transaction,
+      scoped_refptr<IndexedDBBackingStore> backing_store,
+      IndexedDBBackingStore::Transaction* transaction,
+      int64 database_id,
       const IndexedDBBackingStore::Cursor::CursorOptions& cursor_options)
-      : IndexedDBBackingStore::Cursor(transaction, cursor_options) {}
+      : IndexedDBBackingStore::Cursor(backing_store,
+                                      transaction,
+                                      database_id,
+                                      cursor_options) {}
 
   virtual Cursor* Clone() OVERRIDE { return new IndexKeyCursorImpl(this); }
 
@@ -3007,13 +3313,14 @@ bool IndexKeyCursorImpl::LoadCurrentRow() {
 
   std::string result;
   bool found = false;
-  leveldb::Status s = transaction_->Get(primary_leveldb_key, &result, &found);
+  leveldb::Status s =
+      transaction_->transaction()->Get(primary_leveldb_key, &result, &found);
   if (!s.ok()) {
     INTERNAL_READ_ERROR_UNTESTED(LOAD_CURRENT_ROW);
     return false;
   }
   if (!found) {
-    transaction_->Remove(iterator_->Key());
+    transaction_->transaction()->Remove(iterator_->Key());
     return false;
   }
   if (!result.size()) {
@@ -3029,7 +3336,7 @@ bool IndexKeyCursorImpl::LoadCurrentRow() {
   }
 
   if (object_store_data_version != index_data_version) {
-    transaction_->Remove(iterator_->Key());
+    transaction_->transaction()->Remove(iterator_->Key());
     return false;
   }
 
@@ -3039,9 +3346,14 @@ bool IndexKeyCursorImpl::LoadCurrentRow() {
 class IndexCursorImpl : public IndexedDBBackingStore::Cursor {
  public:
   IndexCursorImpl(
-      LevelDBTransaction* transaction,
+      scoped_refptr<IndexedDBBackingStore> backing_store,
+      IndexedDBBackingStore::Transaction* transaction,
+      int64 database_id,
       const IndexedDBBackingStore::Cursor::CursorOptions& cursor_options)
-      : IndexedDBBackingStore::Cursor(transaction, cursor_options) {}
+      : IndexedDBBackingStore::Cursor(backing_store,
+                                      transaction,
+                                      database_id,
+                                      cursor_options) {}
 
   virtual Cursor* Clone() OVERRIDE { return new IndexCursorImpl(this); }
 
@@ -3107,6 +3419,7 @@ bool IndexCursorImpl::LoadCurrentRow() {
     return false;
   }
 
+  DCHECK_EQ(index_data_key.DatabaseId(), database_id_);
   primary_leveldb_key_ =
       ObjectStoreDataKey::Encode(index_data_key.DatabaseId(),
                                  index_data_key.ObjectStoreId(),
@@ -3114,13 +3427,14 @@ bool IndexCursorImpl::LoadCurrentRow() {
 
   std::string result;
   bool found = false;
-  leveldb::Status s = transaction_->Get(primary_leveldb_key_, &result, &found);
+  leveldb::Status s =
+      transaction_->transaction()->Get(primary_leveldb_key_, &result, &found);
   if (!s.ok()) {
     INTERNAL_READ_ERROR_UNTESTED(LOAD_CURRENT_ROW);
     return false;
   }
   if (!found) {
-    transaction_->Remove(iterator_->Key());
+    transaction_->transaction()->Remove(iterator_->Key());
     return false;
   }
   if (!result.size()) {
@@ -3136,12 +3450,14 @@ bool IndexCursorImpl::LoadCurrentRow() {
   }
 
   if (object_store_data_version != index_data_version) {
-    transaction_->Remove(iterator_->Key());
+    transaction_->transaction()->Remove(iterator_->Key());
     return false;
   }
 
   current_value_.bits = slice.as_string();
-  return true;
+  return transaction_->GetBlobInfoForRecord(database_id_,
+                                            primary_leveldb_key_,
+                                            &current_value_).ok();
 }
 
 bool ObjectStoreCursorOptions(
@@ -3308,8 +3624,8 @@ IndexedDBBackingStore::OpenObjectStoreCursor(
                                 direction,
                                 &cursor_options))
     return scoped_ptr<IndexedDBBackingStore::Cursor>();
-  scoped_ptr<ObjectStoreCursorImpl> cursor(
-      new ObjectStoreCursorImpl(leveldb_transaction, cursor_options));
+  scoped_ptr<ObjectStoreCursorImpl> cursor(new ObjectStoreCursorImpl(
+      this, transaction, database_id, cursor_options));
   if (!cursor->FirstSeek(s))
     return scoped_ptr<IndexedDBBackingStore::Cursor>();
 
@@ -3335,8 +3651,8 @@ IndexedDBBackingStore::OpenObjectStoreKeyCursor(
                                 direction,
                                 &cursor_options))
     return scoped_ptr<IndexedDBBackingStore::Cursor>();
-  scoped_ptr<ObjectStoreKeyCursorImpl> cursor(
-      new ObjectStoreKeyCursorImpl(leveldb_transaction, cursor_options));
+  scoped_ptr<ObjectStoreKeyCursorImpl> cursor(new ObjectStoreKeyCursorImpl(
+      this, transaction, database_id, cursor_options));
   if (!cursor->FirstSeek(s))
     return scoped_ptr<IndexedDBBackingStore::Cursor>();
 
@@ -3365,7 +3681,7 @@ IndexedDBBackingStore::OpenIndexKeyCursor(
                           &cursor_options))
     return scoped_ptr<IndexedDBBackingStore::Cursor>();
   scoped_ptr<IndexKeyCursorImpl> cursor(
-      new IndexKeyCursorImpl(leveldb_transaction, cursor_options));
+      new IndexKeyCursorImpl(this, transaction, database_id, cursor_options));
   if (!cursor->FirstSeek(s))
     return scoped_ptr<IndexedDBBackingStore::Cursor>();
 
@@ -3393,7 +3709,7 @@ IndexedDBBackingStore::OpenIndexCursor(
                           &cursor_options))
     return scoped_ptr<IndexedDBBackingStore::Cursor>();
   scoped_ptr<IndexCursorImpl> cursor(
-      new IndexCursorImpl(leveldb_transaction, cursor_options));
+      new IndexCursorImpl(this, transaction, database_id, cursor_options));
   if (!cursor->FirstSeek(s))
     return scoped_ptr<IndexedDBBackingStore::Cursor>();