Clean up old legacy preference migration logic.

components/user_prefs/tracked/pref_service_hash_store_contents.h

-// Copyright 2014 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 COMPONENTS_USER_PREFS_TRACKED_PREF_SERVICE_HASH_STORE_CONTENTS_H_
-#define COMPONENTS_USER_PREFS_TRACKED_PREF_SERVICE_HASH_STORE_CONTENTS_H_
-
-#include <string>
-
-#include "base/compiler_specific.h"
-#include "base/macros.h"
-#include "components/user_prefs/tracked/hash_store_contents.h"
-
-class PrefRegistrySimple;
-class PrefService;
-
-// Implements HashStoreContents by storing hashes in a PrefService. Multiple
-// separate hash stores may coexist in the PrefService by using distinct hash
-// store IDs.
-// TODO(erikwright): This class is only used to recreate preference state as in
-// M35, to test migration behaviour. Remove this class when
-// ProfilePrefStoreManagerTest no longer depends on it.
-class PrefServiceHashStoreContents : public HashStoreContents {
- public:
-  // Constructs a HashStoreContents that stores hashes in |pref_service|.
-  // Multiple hash stores can use the same |pref_service| with distinct
-  // |hash_store_id|s.
-  //
-  // |pref_service| must have previously been configured using |RegisterPrefs|.
-  PrefServiceHashStoreContents(const std::string& hash_store_id,
-                               PrefService* pref_service);
-
-  // A dictionary pref which maps profile names to dictionary values which hold
-  // hashes of profile prefs that we track to detect changes that happen outside
-  // of Chrome.
-  static const char kProfilePreferenceHashes[];
-
-  // The name of a dict that is stored as a child of
-  // |prefs::kProfilePreferenceHashes|. Each child node is a string whose name
-  // is a hash store ID and whose value is the super MAC for the corresponding
-  // hash store.
-  static const char kHashOfHashesDict[];
-
-  // The name of a dict that is stored as a child of
-  // |prefs::kProfilePreferenceHashes|. Each child node is a number whose name
-  // is a hash store ID and whose value is the version of the corresponding
-  // hash store.
-  static const char kStoreVersionsDict[];
-
-  // Registers required preferences.
-  static void RegisterPrefs(PrefRegistrySimple* registry);
-
-  // Deletes stored hashes for all profiles from |pref_service|.
-  static void ResetAllPrefHashStores(PrefService* pref_service);
-
-  // HashStoreContents implementation
-  std::string hash_store_id() const override;
-  void Reset() override;
-  bool IsInitialized() const override;
-  const base::DictionaryValue* GetContents() const override;
-  std::unique_ptr<MutableDictionary> GetMutableContents() override;
-  std::string GetSuperMac() const override;
-  void SetSuperMac(const std::string& super_mac) override;
-
- private:
-  const std::string hash_store_id_;
-  PrefService* pref_service_;
-
-  DISALLOW_COPY_AND_ASSIGN(PrefServiceHashStoreContents);
-};
-
-#endif  // COMPONENTS_PREFS_TRACKED_PREF_SERVICE_HASH_STORE_CONTENTS_H_