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diff --git a/chrome/browser/pref_member.h b/chrome/browser/pref_member.h
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+++ b/chrome/browser/pref_member.h
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+// Copyright (c) 2006-2008 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.
+//
+// A helper class that stays in sync with a preference (bool, int, real, or
+// string).  For example:
+//
+// class MyClass {
+//  public:
+//   MyClass(PrefService* prefs) {
+//     my_string_.Init(prefs::kHomePage, prefs, NULL /* no observer */);
+//   }
+//  private:
+//   StringPrefMember my_string_;
+// };
+//
+// my_string_ should stay in sync with the prefs::kHomePage pref and will
+// update if either the pref changes or if my_string_.SetValue is called.
+//
+// An optional observer can be passed into the Init method which can be used to
+// notify MyClass of changes. Note that if you use SetValue(), the observer
+// will not be notified.
+
+#ifndef CHROME_BROWSER_PREF_MEMBER_H_
+#define CHROME_BROWSER_PREF_MEMBER_H_
+
+#include <string>
+
+#include "base/basictypes.h"
+#include "chrome/common/notification_observer.h"
+
+class PrefService;
+
+namespace subtle {
+
+class PrefMemberBase : public NotificationObserver {
+ protected:
+  PrefMemberBase();
+  virtual ~PrefMemberBase();
+
+  // See PrefMember<> for description.
+  void Init(const wchar_t* pref_name, PrefService* prefs,
+            NotificationObserver* observer);
+
+  // NotificationObserver
+  virtual void Observe(NotificationType type,
+                       const NotificationSource& source,
+                       const NotificationDetails& details);
+
+  void VerifyValuePrefName();
+
+  // This methods is used to do the actual sync with pref of the specified type.
+  virtual void UpdateValueFromPref() = 0;
+
+  const std::wstring& pref_name() const { return pref_name_; }
+  PrefService* prefs() { return prefs_; }
+
+ // Ordered the members to compact the class instance.
+ private:
+  std::wstring pref_name_;
+  NotificationObserver* observer_;
+  PrefService* prefs_;
+
+ protected:
+  bool is_synced_;
+  bool setting_value_;
+};
+
+}  // namespace subtle
+
+
+template <typename ValueType>
+class PrefMember : public subtle::PrefMemberBase {
+ public:
+  // Defer initialization to an Init method so it's easy to make this class be
+  // a member variable.
+  PrefMember() { }
+  virtual ~PrefMember() { }
+
+  // Do the actual initialization of the class.  |observer| may be null if you
+  // don't want any notifications of changes.
+  void Init(const wchar_t* pref_name, PrefService* prefs,
+            NotificationObserver* observer) {
+    subtle::PrefMemberBase::Init(pref_name, prefs, observer);
+  }
+
+  // Retrieve the value of the member variable.
+  ValueType GetValue() {
+    VerifyValuePrefName();
+    // We lazily fetch the value from the pref service the first time GetValue
+    // is called.
+    if (!is_synced_) {
+      UpdateValueFromPref();
+      is_synced_ = true;
+    }
+    return value_;
+  }
+
+  // Provided as a convenience.
+  ValueType operator*() {
+    return GetValue();
+  }
+
+  // Set the value of the member variable.
+  void SetValue(const ValueType& value) {
+    VerifyValuePrefName();
+    setting_value_ = true;
+    UpdatePref(value);
+    setting_value_ = false;
+  }
+
+ protected:
+  // This methods is used to do the actual sync with pref of the specified type.
+  virtual void UpdatePref(const ValueType& value) = 0;
+
+  // We cache the value of the pref so we don't have to keep walking the pref
+  // tree.
+  ValueType value_;
+};
+
+///////////////////////////////////////////////////////////////////////////////
+// Implementations of Boolean, Integer, Real, and String PrefMember below.
+
+class BooleanPrefMember : public PrefMember<bool> {
+ public:
+  BooleanPrefMember() : PrefMember<bool>() { }
+  virtual ~BooleanPrefMember() { }
+
+ protected:
+  virtual void UpdateValueFromPref();
+  virtual void UpdatePref(const bool& value);
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(BooleanPrefMember);
+};
+
+class IntegerPrefMember : public PrefMember<int> {
+ public:
+  IntegerPrefMember() : PrefMember<int>() { }
+  virtual ~IntegerPrefMember() { }
+
+ protected:
+  virtual void UpdateValueFromPref();
+  virtual void UpdatePref(const int& value);
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(IntegerPrefMember);
+};
+
+class RealPrefMember : public PrefMember<double> {
+ public:
+  RealPrefMember() : PrefMember<double>() { }
+  virtual ~RealPrefMember() { }
+
+ protected:
+  virtual void UpdateValueFromPref();
+  virtual void UpdatePref(const double& value);
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(RealPrefMember);
+};
+
+class StringPrefMember : public PrefMember<std::wstring> {
+ public:
+  StringPrefMember() : PrefMember<std::wstring>() { }
+  virtual ~StringPrefMember() { }
+
+ protected:
+  virtual void UpdateValueFromPref();
+  virtual void UpdatePref(const std::wstring& value);
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(StringPrefMember);
+};
+
+#endif  // CHROME_BROWSER_PREF_MEMBER_H_