IndexedDB: Fix trivial cpplint.py errors

content/browser/indexed_db/indexed_db_factory.h

 // 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.
 
 #ifndef CONTENT_BROWSER_INDEXED_DB_INDEXED_DB_FACTORY_H_
 #define CONTENT_BROWSER_INDEXED_DB_INDEXED_DB_FACTORY_H_
 
 #include <map>
 #include <set>
+#include <string>
+#include <utility>
 
 #include "base/basictypes.h"
 #include "base/files/file_path.h"
 #include "base/memory/ref_counted.h"
 #include "base/strings/string16.h"
 #include "content/browser/indexed_db/indexed_db_callbacks.h"
 #include "content/browser/indexed_db/indexed_db_database.h"
 #include "content/browser/indexed_db/indexed_db_database_callbacks.h"
 #include "content/common/content_export.h"
 #include "url/gurl.h"
@@ skipping 123 matching lines @@
   std::set<scoped_refptr<IndexedDBBackingStore> > session_only_backing_stores_;
   IndexedDBBackingStoreMap backing_stores_with_active_blobs_;
   std::set<GURL> backends_opened_since_boot_;
 
   DISALLOW_COPY_AND_ASSIGN(IndexedDBFactory);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_INDEXED_DB_INDEXED_DB_FACTORY_H_