RefCounted types should not have public destructors, chrome/ remaining parts

chrome/common/persistent_pref_store.h

 // Copyright (c) 2012 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_COMMON_PERSISTENT_PREF_STORE_H_
 #define CHROME_COMMON_PERSISTENT_PREF_STORE_H_
 #pragma once
 
 #include <string>
 
 #include <chrome/common/pref_store.h>
 
 // This interface is complementary to the PrefStore interface, declaring
 // additional functionality that adds support for setting values and persisting
 // the data to some backing store.
 class PersistentPrefStore : public PrefStore {
  public:
-  virtual ~PersistentPrefStore() {}
-
   // Unique integer code for each type of error so we can report them
   // distinctly in a histogram.
   // NOTE: Don't change the order here as it will change the server's meaning
   // of the histogram.
   enum PrefReadError {
     PREF_READ_ERROR_NONE = 0,
     PREF_READ_ERROR_JSON_PARSE,
     PREF_READ_ERROR_JSON_TYPE,
     PREF_READ_ERROR_ACCESS_DENIED,
     PREF_READ_ERROR_FILE_OTHER,
@@ skipping 52 matching lines @@
   virtual PrefReadError ReadPrefs() = 0;
 
   // Reads the preferences from disk asynchronously. Notifies observers via
   // "PrefStore::OnInitializationCompleted" when done. Also it fires
   // |error_delegate| if it is not NULL and reading error has occurred.
   // Owns |error_delegate|.
   virtual void ReadPrefsAsync(ReadErrorDelegate* error_delegate) = 0;
 
   // Lands any pending writes to disk.
   virtual void CommitPendingWrite() = 0;
+
+ protected:
+  virtual ~PersistentPrefStore() {}
 };
 
 #endif  // CHROME_COMMON_PERSISTENT_PREF_STORE_H_