content: Cleanup class/struct forward declarations

content/browser/indexed_db/indexed_db_connection.h

 // Copyright 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_CONNECTION_H_
 #define CONTENT_BROWSER_INDEXED_DB_INDEXED_DB_CONNECTION_H_
 
 #include <memory>
 #include <vector>
 
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
 #include "content/browser/indexed_db/indexed_db_database.h"
 #include "content/browser/indexed_db/indexed_db_database_callbacks.h"
 #include "content/browser/indexed_db/indexed_db_observer.h"
 
 namespace content {
-class IndexedDBDatabaseError;
 
 class CONTENT_EXPORT IndexedDBConnection {
  public:
   IndexedDBConnection(scoped_refptr<IndexedDBDatabase> db,
                       scoped_refptr<IndexedDBDatabaseCallbacks> callbacks);
   virtual ~IndexedDBConnection();
 
   // These methods are virtual to allow subclassing in unit tests.
   virtual void ForceClose();
   virtual void Close();
@@ skipping 31 matching lines @@
   scoped_refptr<IndexedDBDatabaseCallbacks> callbacks_;
   std::vector<std::unique_ptr<IndexedDBObserver>> active_observers_;
   base::WeakPtrFactory<IndexedDBConnection> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(IndexedDBConnection);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_INDEXED_DB_INDEXED_DB_CONNECTION_H_