Introduce incognito preference settings.

chrome/browser/prefs/pref_value_map.h

Index: chrome/browser/prefs/pref_value_map.h
diff --git a/chrome/browser/prefs/pref_value_map.h b/chrome/browser/prefs/pref_value_map.h
index 0e999208840f9aedd1a3f67053f35fcb91757d5e..19aeb0599f06f9fa7f219b1f2bf6faffa191b1ee 100644
--- a/chrome/browser/prefs/pref_value_map.h
+++ b/chrome/browser/prefs/pref_value_map.h
@@ -1,4 +1,4 @@
-// Copyright (c) 2010 The Chromium Authors. All rights reserved.
+// 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.
 
@@ -17,6 +17,9 @@ class Value;
 // A generic string to value map used by the PrefStore implementations.
 class PrefValueMap {
  public:
+  typedef std::map<std::string, Value*>::iterator iterator;
+  typedef std::map<std::string, Value*>::const_iterator const_iterator;
+
   PrefValueMap();
   virtual ~PrefValueMap();
 
@@ -36,6 +39,11 @@ class PrefValueMap {
   // Clears the map.
   void Clear();
 
+  iterator begin();
+  iterator end();
+  const_iterator begin() const;
+  const_iterator end() const;
+
   // Gets a boolean value for |key| and stores it in |value|. Returns true if
   // the value was found and of the proper type.
   bool GetBoolean(const std::string& key, bool* value) const;