NTP4/apps page: fix page stickiness

chrome/browser/ui/webui/ntp/new_tab_page_handler.h

-// Copyright (c) 2012 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_NTP_NEW_TAB_PAGE_HANDLER_H_
-#define CHROME_BROWSER_UI_WEBUI_NTP_NEW_TAB_PAGE_HANDLER_H_
-
-#include <stddef.h>
-
-#include "base/macros.h"
-#include "base/memory/weak_ptr.h"
-#include "base/values.h"
-#include "content/public/browser/web_ui_message_handler.h"
-
-class PrefRegistrySimple;
-class Profile;
-
-namespace user_prefs {
-class PrefRegistrySyncable;
-}
-
-// Handler for general New Tab Page functionality that does not belong in a
-// more specialized handler.
-class NewTabPageHandler : public content::WebUIMessageHandler,
-                          public base::SupportsWeakPtr<NewTabPageHandler> {
- public:
-  NewTabPageHandler();
-
-  // Register NTP per-profile preferences.
-  static void RegisterProfilePrefs(user_prefs::PrefRegistrySyncable* registry);
-
-  // Registers values (strings etc.) for the page.
-  static void GetLocalizedValues(Profile* profile,
-      base::DictionaryValue* values);
-
- private:
-  ~NewTabPageHandler() override;
-
-  // WebUIMessageHandler implementation.
-  void RegisterMessages() override;
-
-  // Callback for "pageSelected".
-  void HandlePageSelected(const base::ListValue* args);
-
-  // Tracks the number of times the user has switches pages (for UMA).
-  size_t page_switch_count_;
-
-  // The purpose of this enum is to track which page on the NTP is showing.
-  // The lower 10 bits of kNtpShownPage are used for the index within the page
-  // group, and the rest of the bits are used for the page group ID (defined
-  // here).
-  static const int kPageIdOffset = 10;
-  enum {
-    INDEX_MASK = (1 << kPageIdOffset) - 1,
-    APPS_PAGE_ID = 2 << kPageIdOffset,
-    LAST_PAGE_ID = APPS_PAGE_ID,
-  };
-  static const int kHistogramEnumerationMax =
-      (LAST_PAGE_ID >> kPageIdOffset) + 1;
-
-  DISALLOW_COPY_AND_ASSIGN(NewTabPageHandler);
-};
-
-#endif  // CHROME_BROWSER_UI_WEBUI_NTP_NEW_TAB_PAGE_HANDLER_H_