ntp: remove ShownSectionHandler and all references to it

chrome/common/pref_names.h

 // 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.
 
 // Constants for the names of various preferences, for easier changing.
 
 #ifndef CHROME_COMMON_PREF_NAMES_H_
 #define CHROME_COMMON_PREF_NAMES_H_
 #pragma once
 
@@ skipping 433 matching lines @@
 
 extern const char kNTP4IntroDisplayCount[];
 extern const char kNTPMostVisitedURLsBlacklist[];
 extern const char kNTPMostVisitedPinnedURLs[];
 extern const char kNTPPromoResourceCache[];
 extern const char kNTPPromoResourceCacheUpdate[];
 extern const char kNTPPromoResourceServer[];
 extern const char kNTPDateResourceServer[];
 extern const char kNTPShownBookmarksFolder[];
 extern const char kNTPShownPage[];
-extern const char kNTPShownSections[];
-extern const char kNTPPrefVersion[];
 extern const char kNTPCustomLogoStart[];
 extern const char kNTPCustomLogoEnd[];
 extern const char kNTPPromoVersion[];
 extern const char kNTPPromoLocale[];
 extern const char kNTPPromoStart[];
 extern const char kNTPPromoEnd[];
 extern const char kNTPPromoLine[];
 extern const char kNTPPromoClosed[];
 extern const char kNTPPromoGroup[];
 extern const char kNTPPromoGroupTimeSlice[];
@@ skipping 140 matching lines @@
 
 extern const char kDevicePolicyRefreshRate[];
 extern const char kUserPolicyRefreshRate[];
 
 extern const char kRecoveryComponentVersion[];
 extern const char kComponentUpdaterState[];
 
 }  // namespace prefs
 
 #endif  // CHROME_COMMON_PREF_NAMES_H_