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diff --git a/chrome/browser/ui/webui/shown_sections_handler.h b/chrome/browser/ui/webui/shown_sections_handler.h
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+++ b/chrome/browser/ui/webui/shown_sections_handler.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_UI_WEBUI_SHOWN_SECTIONS_HANDLER_H_
+#define CHROME_BROWSER_UI_WEBUI_SHOWN_SECTIONS_HANDLER_H_
+#pragma once
+
+#include "chrome/browser/prefs/pref_change_registrar.h"
+#include "chrome/common/notification_observer.h"
+#include "content/browser/webui/web_ui.h"
+
+class Extension;
+class Value;
+class PrefService;
+
+// Use for the shown sections bitmask.
+// Currently, only the THUMB and APPS sections can be toggled by the user. Other
+// sections are shown automatically if they have data, and hidden otherwise.
+enum Section {
+  // If one of these is set, the corresponding section shows large thumbnails,
+  // else it shows only a small overview list.
+  THUMB = 1 << 0,
+  APPS = 1 << 6,
+
+  // We use the low 16 bits for sections, the high 16 bits for menu mode.
+  ALL_SECTIONS_MASK = 0x0000FFFF,
+
+  // If one of these is set, then the corresponding section is shown in a menu
+  // at the bottom of the NTP and no data is directly visible on the NTP.
+  MENU_THUMB = 1 << (0 + 16),
+  MENU_RECENT = 1 << (2 + 16),
+  MENU_APPS = 1 << (6 + 16),
+};
+
+class ShownSectionsHandler : public WebUIMessageHandler,
+                             public NotificationObserver {
+ public:
+  explicit ShownSectionsHandler(PrefService* pref_service);
+  virtual ~ShownSectionsHandler() {}
+
+  // Helper to get the current shown sections.
+  static int GetShownSections(PrefService* pref_service);
+
+  // Expands |section|, collapsing any previously expanded section. This is the
+  // same thing that happens if a user clicks on |section|.
+  static void SetShownSection(PrefService* prefs, Section section);
+
+  // WebUIMessageHandler implementation.
+  virtual void RegisterMessages();
+
+  // NotificationObserver implementation.
+  virtual void Observe(NotificationType type,
+                       const NotificationSource& source,
+                       const NotificationDetails& details);
+
+  // Callback for "getShownSections" message.
+  void HandleGetShownSections(const ListValue* args);
+
+  // Callback for "setShownSections" message.
+  void HandleSetShownSections(const ListValue* args);
+
+  static void RegisterUserPrefs(PrefService* pref_service);
+
+  static void MigrateUserPrefs(PrefService* pref_service,
+                               int old_pref_version,
+                               int new_pref_version);
+
+  static void OnExtensionInstalled(PrefService* prefs,
+                                   const Extension* extension);
+
+ private:
+  PrefService* pref_service_;
+  PrefChangeRegistrar pref_registrar_;
+
+  DISALLOW_COPY_AND_ASSIGN(ShownSectionsHandler);
+};
+
+#endif  // CHROME_BROWSER_UI_WEBUI_SHOWN_SECTIONS_HANDLER_H_