RefCounted types should not have public destructors, delegate cleanup

chrome/common/important_file_writer.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_COMMON_IMPORTANT_FILE_WRITER_H_
 #define CHROME_COMMON_IMPORTANT_FILE_WRITER_H_
 #pragma once
 
 #include <string>
 
@@ skipping 24 matching lines @@
 // temporary file to target filename.
 //
 // If you want to know more about this approach and ext3/ext4 fsync issues, see
 // http://valhenson.livejournal.com/37921.html
 class ImportantFileWriter : public base::NonThreadSafe {
  public:
   // Used by ScheduleSave to lazily provide the data to be saved. Allows us
   // to also batch data serializations.
   class DataSerializer {
    public:
-    virtual ~DataSerializer() {}
-
     // Should put serialized string in |data| and return true on successful
     // serialization. Will be called on the same thread on which
     // ImportantFileWriter has been created.
     virtual bool SerializeData(std::string* data) = 0;
+
+   protected:
+    virtual ~DataSerializer() {}
   };
 
   // Initialize the writer.
   // |path| is the name of file to write.
   // |file_message_loop_proxy| is the MessageLoopProxy for a thread on which
   // file I/O can be done.
   // All non-const methods, ctor and dtor must be called on the same thread.
   ImportantFileWriter(const FilePath& path,
                       base::MessageLoopProxy* file_message_loop_proxy);
 
@@ skipping 43 matching lines @@
   // Serializer which will provide the data to be saved.
   DataSerializer* serializer_;
 
   // Time delta after which scheduled data will be written to disk.
   base::TimeDelta commit_interval_;
 
   DISALLOW_COPY_AND_ASSIGN(ImportantFileWriter);
 };
 
 #endif  // CHROME_COMMON_IMPORTANT_FILE_WRITER_H_