Add the "virtual" keyword on method overrides that are missing it.

base/values.h

 // Copyright (c) 2010 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 106 matching lines @@
 
   DISALLOW_COPY_AND_ASSIGN(Value);
 };
 
 // FundamentalValue represents the simple fundamental types of values.
 class FundamentalValue : public Value {
  public:
   explicit FundamentalValue(bool in_value);
   explicit FundamentalValue(int in_value);
   explicit FundamentalValue(double in_value);
-  ~FundamentalValue();
+  virtual ~FundamentalValue();
 
   // Subclassed methods
   virtual bool GetAsBoolean(bool* out_value) const;
   virtual bool GetAsInteger(int* out_value) const;
   virtual bool GetAsReal(double* out_value) const;
   virtual Value* DeepCopy() const;
   virtual bool Equals(const Value* other) const;
 
  private:
   union {
     bool boolean_value_;
     int integer_value_;
     double real_value_;
   };
 
   DISALLOW_COPY_AND_ASSIGN(FundamentalValue);
 };
 
 class StringValue : public Value {
  public:
   // Initializes a StringValue with a UTF-8 narrow character string.
   explicit StringValue(const std::string& in_value);
 
   // Initializes a StringValue with a string16.
   explicit StringValue(const string16& in_value);
 
-  ~StringValue();
+  virtual ~StringValue();
 
   // Subclassed methods
-  bool GetAsString(std::string* out_value) const;
-  bool GetAsString(string16* out_value) const;
-  Value* DeepCopy() const;
+  virtual bool GetAsString(std::string* out_value) const;
+  virtual bool GetAsString(string16* out_value) const;
+  virtual Value* DeepCopy() const;
   virtual bool Equals(const Value* other) const;
 
  private:
   std::string value_;
 
   DISALLOW_COPY_AND_ASSIGN(StringValue);
 };
 
 class BinaryValue: public Value {
  public:
   // Creates a Value to represent a binary buffer.  The new object takes
   // ownership of the pointer passed in, if successful.
   // Returns NULL if buffer is NULL.
   static BinaryValue* Create(char* buffer, size_t size);
 
   // For situations where you want to keep ownership of your buffer, this
   // factory method creates a new BinaryValue by copying the contents of the
   // buffer that's passed in.
   // Returns NULL if buffer is NULL.
   static BinaryValue* CreateWithCopiedBuffer(const char* buffer, size_t size);
 
-  ~BinaryValue();
+  virtual ~BinaryValue();
 
   // Subclassed methods
-  Value* DeepCopy() const;
+  virtual Value* DeepCopy() const;
   virtual bool Equals(const Value* other) const;
 
   size_t GetSize() const { return size_; }
   char* GetBuffer() { return buffer_; }
   const char* GetBuffer() const { return buffer_; }
 
  private:
   // Constructor is private so that only objects with valid buffer pointers
   // and size values can be created.
   BinaryValue(char* buffer, size_t size);
 
   char* buffer_;
   size_t size_;
 
   DISALLOW_COPY_AND_ASSIGN(BinaryValue);
 };
 
 // DictionaryValue provides a key-value dictionary with (optional) "path"
 // parsing for recursive access; see the comment at the top of the file. Keys
 // are |std::string|s and should be UTF-8 encoded.
 class DictionaryValue : public Value {
  public:
   DictionaryValue();
-  ~DictionaryValue();
+  virtual ~DictionaryValue();
 
   // Subclassed methods
-  Value* DeepCopy() const;
+  virtual Value* DeepCopy() const;
   virtual bool Equals(const Value* other) const;
 
   // Returns true if the current dictionary has a value for the given key.
   bool HasKey(const std::string& key) const;
 
   // Returns the number of Values in this dictionary.
   size_t size() const { return dictionary_.size(); }
 
   // Returns whether the dictionary is empty.
   bool empty() const { return dictionary_.empty(); }
@@ skipping 139 matching lines @@
 };
 
 // This type of Value represents a list of other Value values.
 class ListValue : public Value {
  public:
   ListValue();
   ~ListValue();
 
   // Subclassed methods
   virtual bool GetAsList(ListValue** out_value);
-  Value* DeepCopy() const;
+  virtual Value* DeepCopy() const;
   virtual bool Equals(const Value* other) const;
 
   // 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 76 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_