IndexedDB: Ignore duplicate transaction IDs sent by renderer

content/browser/indexed_db/indexed_db_database.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_database.h"
 
 #include <math.h>
 #include <set>
 
 #include "base/auto_reset.h"
@@ skipping 1380 matching lines @@
   }
 }
 
 void IndexedDBDatabase::CreateTransaction(
     int64 transaction_id,
     IndexedDBConnection* connection,
     const std::vector<int64>& object_store_ids,
     uint16 mode) {
 
   DCHECK(connections_.has(connection));
+  DCHECK(transactions_.find(transaction_id) == transactions_.end());
+  if (transactions_.find(transaction_id) != transactions_.end())
+    return;
 
   scoped_refptr<IndexedDBTransaction> transaction = new IndexedDBTransaction(
       transaction_id,
       connection->callbacks(),
       std::set<int64>(object_store_ids.begin(), object_store_ids.end()),
       static_cast<indexed_db::TransactionMode>(mode),
       this);
-  DCHECK(transactions_.find(transaction_id) == transactions_.end());
   transactions_[transaction_id] = transaction;
 }
 
 bool IndexedDBDatabase::IsOpenConnectionBlocked() const {
   return !pending_delete_calls_.empty() ||
          running_version_change_transaction_ ||
          pending_run_version_change_transaction_call_;
 }
 
 void IndexedDBDatabase::OpenConnection(
@@ skipping 302 matching lines @@
     const string16& previous_version,
     int64 previous_int_version,
     IndexedDBTransaction* transaction) {
   IDB_TRACE("IndexedDBDatabase::VersionChangeAbortOperation");
   DCHECK(!transaction);
   metadata_.version = previous_version;
   metadata_.int_version = previous_int_version;
 }
 
 }  // namespace content