Introduce incognito preference settings.

chrome/browser/prefs/overlay_persistent_pref_store.h

Index: chrome/browser/prefs/overlay_persistent_pref_store.h
diff --git a/chrome/browser/prefs/overlay_persistent_pref_store.h b/chrome/browser/prefs/overlay_persistent_pref_store.h
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+++ b/chrome/browser/prefs/overlay_persistent_pref_store.h
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+// 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.
+
+#ifndef CHROME_BROWSER_PREFS_OVERLAY_PERSISTENT_PREF_STORE_H_
+#define CHROME_BROWSER_PREFS_OVERLAY_PERSISTENT_PREF_STORE_H_
+#pragma once
+
+#include <string>
+
+#include "base/basictypes.h"
+#include "base/observer_list.h"
+#include "base/ref_counted.h"
+#include "chrome/browser/prefs/pref_value_map.h"
+#include "chrome/common/persistent_pref_store.h"
+
+// PersistentPrefStore that directs all write operations into a in-memory
+// PrefValueMap. Read operations are first answered by the PrefValueMap.
+// If the PrefValueMap does not contain a value for the requested key,
+// the look-up is passed on to an underlying PersistentPrefStore |underlay_|.
+class OverlayPersistentPrefStore : public PersistentPrefStore,
+                                   public PrefStore::Observer {
+ public:
+  explicit OverlayPersistentPrefStore(PersistentPrefStore* underlay);
+  virtual ~OverlayPersistentPrefStore();
+
+  // Methods of PrefStore.
+  virtual void AddObserver(PrefStore::Observer* observer);
+  virtual void RemoveObserver(PrefStore::Observer* observer);
+  virtual bool IsInitializationComplete() const;
+  virtual ReadResult GetValue(const std::string& key, Value** result) const;
+
+  // Methods of PersistentPrefStore.
+  virtual void SetValue(const std::string& key, Value* value);
+  virtual void SetValueSilently(const std::string& key, Value* value);
+  virtual void RemoveValue(const std::string& key);
+  virtual bool ReadOnly() const;
+  virtual PrefReadError ReadPrefs();
+  virtual bool WritePrefs();
+  virtual void ScheduleWritePrefs();
+
+ private:
+  // Methods of PrefStore::Observer.
+  virtual void OnPrefValueChanged(const std::string& key);
+  virtual void OnInitializationCompleted();
+
+  ObserverList<PrefStore::Observer, true> observers_;
+  PrefValueMap overlay_;
+  scoped_refptr<PersistentPrefStore> underlay_;
+
+  DISALLOW_COPY_AND_ASSIGN(OverlayPersistentPrefStore);
+};
+
+#endif  // CHROME_BROWSER_PREFS_OVERLAY_PERSISTENT_PREF_STORE_H_