Add ComputeMac and ComputeSplitMacs methods to pref_hash_store.

components/user_prefs/tracked/pref_hash_store_impl.h

 // Copyright 2013 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_HASH_STORE_IMPL_H_
 #define COMPONENTS_USER_PREFS_TRACKED_PREF_HASH_STORE_IMPL_H_
 
-#include <memory>
-#include <string>
-
 #include "base/compiler_specific.h"
 #include "base/macros.h"
 #include "components/user_prefs/tracked/pref_hash_calculator.h"
 #include "components/user_prefs/tracked/pref_hash_store.h"
 
-class HashStoreContents;
-class PrefHashStoreTransaction;
-
 // Implements PrefHashStoreImpl by storing preference hashes in a
 // HashStoreContents.
 class PrefHashStoreImpl : public PrefHashStore {
  public:
   enum StoreVersion {
     // No hashes have been stored in this PrefHashStore yet.
     VERSION_UNINITIALIZED = 0,
     // The hashes in this PrefHashStore were stored before the introduction
     // of a version number and should be re-initialized.
     VERSION_PRE_MIGRATION = 1,
@@ skipping 13 matching lines @@
   ~PrefHashStoreImpl() override;
 
   // Clears the contents of this PrefHashStore. |IsInitialized()| will return
   // false after this call.
   void Reset();
 
   // PrefHashStore implementation.
   std::unique_ptr<PrefHashStoreTransaction> BeginTransaction(
       HashStoreContents* storage) override;
 
+  std::string ComputeMac(const std::string& path,
+                         const base::Value* new_value) override;
+  std::unique_ptr<base::DictionaryValue> ComputeSplitMacs(
+      const std::string& path,
+      const base::DictionaryValue* split_values) override;
+
  private:
   class PrefHashStoreTransactionImpl;
 
   const PrefHashCalculator pref_hash_calculator_;
   bool use_super_mac_;
 
   DISALLOW_COPY_AND_ASSIGN(PrefHashStoreImpl);
 };
 
 #endif  // COMPONENTS_USER_PREFS_TRACKED_PREF_HASH_STORE_IMPL_H_