Cleanup: Remove unneeded forward declarations in chrome/installer.

chrome/installer/util/registry_key_backup.h

 // Copyright (c) 2011 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 CHROME_INSTALLER_UTIL_REGISTRY_KEY_BACKUP_H_
 #define CHROME_INSTALLER_UTIL_REGISTRY_KEY_BACKUP_H_
 #pragma once
 
 #include <windows.h>
 
-#include <string>
-
 #include "base/basictypes.h"
 #include "base/memory/scoped_ptr.h"
 
-namespace base {
-namespace win {
-class RegKey;
-}  // namespace win
-}  // namespace base
-
 // A container for a registry key, its values, and its subkeys.  We don't use
 // more obvious methods for various reasons:
 // - RegCopyTree isn't supported pre-Vista, so we'd have to do something
 //   different for XP anyway.
 // - SHCopyKey can't copy subkeys into a volatile destination, so we'd have to
 //   worry about polluting the registry.
 // We don't persist security attributes since we only delete keys that we own,
 // and we don't set custom attributes on them anyway.
 class RegistryKeyBackup {
  public:
@@ skipping 17 matching lines @@
  private:
   class KeyData;
 
   // The values and subkeys of the backed-up key.
   scoped_ptr<KeyData> key_data_;
 
   DISALLOW_COPY_AND_ASSIGN(RegistryKeyBackup);
 };
 
 #endif  // CHROME_INSTALLER_UTIL_REGISTRY_KEY_BACKUP_H_