Make proxy settings one atomic dictionary in the PrefStores such that modifications are atomic.

chrome/browser/prefs/pref_service.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 provides a way to access the application's current preferences.
 
 #ifndef CHROME_BROWSER_PREFS_PREF_SERVICE_H_
 #define CHROME_BROWSER_PREFS_PREF_SERVICE_H_
 #pragma once
 
@@ skipping 133 matching lines @@
   void ScheduleSavePersistentPrefs();
 
   // Make the PrefService aware of a pref.
   void RegisterBooleanPref(const char* path, bool default_value);
   void RegisterIntegerPref(const char* path, int default_value);
   void RegisterDoublePref(const char* path, double default_value);
   void RegisterStringPref(const char* path, const std::string& default_value);
   void RegisterFilePathPref(const char* path, const FilePath& default_value);
   void RegisterListPref(const char* path);
   void RegisterDictionaryPref(const char* path);
+  // These take ownership of the default_value:
+  void RegisterListPref(const char* path, ListValue* default_value);
+  void RegisterDictionaryPref(const char* path, DictionaryValue* default_value);
 
   // These variants use a default value from the locale dll instead.
   void RegisterLocalizedBooleanPref(const char* path,
                                     int locale_default_message_id);
   void RegisterLocalizedIntegerPref(const char* path,
                                     int locale_default_message_id);
   void RegisterLocalizedDoublePref(const char* path,
                                    int locale_default_message_id);
   void RegisterLocalizedStringPref(const char* path,
                                    int locale_default_message_id);
@@ skipping 140 matching lines @@
 
   // Local cache of registered Preference objects. The default_store_
   // is authoritative with respect to what the types and default values
   // of registered preferences are.
   mutable PreferenceSet prefs_;
 
   DISALLOW_COPY_AND_ASSIGN(PrefService);
 };
 
 #endif  // CHROME_BROWSER_PREFS_PREF_SERVICE_H_