Virtual destructors should have virtual keyword.

base/values.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.
 
 // This file specifies a recursive data storage class called Value intended for
 // storing setting and other persistable data.  It includes the ability to
 // specify (recursive) lists and dictionaries, so it's fairly expressive.
 // However, the API is optimized for the common case, namely storing a
 // hierarchical tree of simple values.  Given a DictionaryValue root, you can
 // easily do things like:
@@ skipping 337 matching lines @@
   DISALLOW_COPY_AND_ASSIGN(DictionaryValue);
 };
 
 // This type of Value represents a list of other Value values.
 class BASE_API ListValue : public Value {
  public:
   typedef ValueVector::iterator iterator;
   typedef ValueVector::const_iterator const_iterator;
 
   ListValue();
-  ~ListValue();
+  virtual ~ListValue();
 
   // Clears the contents of this ListValue
   void Clear();
 
   // Returns the number of Values in this list.
   size_t GetSize() const { return list_.size(); }
 
   // Returns whether the list is empty.
   bool empty() const { return list_.empty(); }
 
@@ skipping 78 matching lines @@
   // This method deserializes the subclass-specific format into a Value object.
   // If the return value is non-NULL, the caller takes ownership of returned
   // Value. If the return value is NULL, and if error_code is non-NULL,
   // error_code will be set with the underlying error.
   // If |error_message| is non-null, it will be filled in with a formatted
   // error message including the location of the error if appropriate.
   virtual Value* Deserialize(int* error_code, std::string* error_str) = 0;
 };
 
 #endif  // BASE_VALUES_H_