Fix for Bug 50726 "Save extension list and "winning" prefs from extensions"

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 82 matching lines @@
   virtual bool GetAsString(std::string* out_value) const;
   virtual bool GetAsString(string16* out_value) const;
 
   // This creates a deep copy of the entire Value tree, and returns a pointer
   // to the copy.  The caller gets ownership of the copy, of course.
   virtual Value* DeepCopy() const;
 
   // Compares if two Value objects have equal contents.
   virtual bool Equals(const Value* other) const;
 
+  // Compares if two Value objects have equal contents. Can handle NULLs.
+  // NULLs are considered equal but different from Value::CreateNullValue().
+  static bool Equals(const Value* a, const Value* b);
+
  protected:
   // This isn't safe for end-users (they should use the Create*Value()
   // static methods above), but it's useful for subclasses.
   explicit Value(ValueType type);
 
  private:
   Value();
 
   ValueType type_;
 
@@ skipping 339 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_