Preference provider implementation backed by JSON files in a directory.

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 294 matching lines @@
   bool Remove(const std::wstring& path, Value** out_value);
 
   // Like Remove(), but without special treatment of '.'.  This allows e.g. URLs
   // to be used as paths.
   bool RemoveWithoutPathExpansion(const std::wstring& key, Value** out_value);
 
   // Makes a copy of |this| but doesn't include empty dictionaries and lists in
   // the copy.  This never returns NULL, even if |this| itself is empty.
   DictionaryValue* DeepCopyWithoutEmptyChildren();
 
+  // Merge a given dictionary into this dictionary. This is done recursively,
+  // i.e. any subdictionaries will be merged as well. In case of key collisions,
+  // the passed in dictionary takes precedence and data already present will be
+  // replaced.
+  void MergeDictionary(const DictionaryValue* dictionary);
+
   // This class provides an iterator for the keys in the dictionary.
   // It can't be used to modify the dictionary.
   //
   // YOU SHOULD ALWAYS USE THE XXXWithoutPathExpansion() APIs WITH THESE, NOT
   // THE NORMAL XXX() APIs.  This makes sure things will work correctly if any
   // keys have '.'s in them.
   class key_iterator
     : private std::iterator<std::input_iterator_tag, const std::wstring> {
    public:
     explicit key_iterator(ValueMap::const_iterator itr) { itr_ = itr; }
@@ skipping 111 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_