Add a scoped notifier for pref dictionaries / lists.

chrome/browser/scoped_pref_update.h

Index: chrome/browser/scoped_pref_update.h
diff --git a/chrome/browser/scoped_pref_update.h b/chrome/browser/scoped_pref_update.h
new file mode 100644
index 0000000000000000000000000000000000000000..f50fa48ef68ab8f52d77b17c165a0d5433b3b666
--- /dev/null
+++ b/chrome/browser/scoped_pref_update.h
@@ -0,0 +1,23 @@
+// 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.
+//
+// A helper class that assists preferences in firing notifications when lists
+// are changed.
+
+#ifndef CHROME_BROWSER_SCOPED_PREF_UPDATE_H_
+#define CHROME_BROWSER_SCOPED_PREF_UPDATE_H_
+
+#include "chrome/browser/pref_service.h"
+
+class ScopedPrefUpdate {
+ public:
+  ScopedPrefUpdate(PrefService* service, const wchar_t* path);
+  ~ScopedPrefUpdate();
+
+ private:
+  PrefService* service_;
+  std::wstring path_;
+};
+
+#endif