Delete the PreferenceMACs on profile deletion.

services/preferences/public/cpp/persistent_pref_store_client.h

 // Copyright 2017 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 SERVICES_PREFERENCES_PUBLIC_CPP_PERSISTENT_PREF_STORE_CLIENT_H_
 #define SERVICES_PREFERENCES_PUBLIC_CPP_PERSISTENT_PREF_STORE_CLIENT_H_
 
 #include <map>
 #include <memory>
 #include <set>
@@ skipping 38 matching lines @@
                         uint32_t flags) override;
 
   // PersistentPrefStore:
   bool ReadOnly() const override;
   PrefReadError GetReadError() const override;
   PrefReadError ReadPrefs() override;
   void ReadPrefsAsync(ReadErrorDelegate* error_delegate) override;
   void CommitPendingWrite(base::OnceClosure done_callback) override;
   void SchedulePendingLossyWrites() override;
   void ClearMutableValues() override;
+  void OnStoreDeletionFromDisk() override;
 
  protected:
   // base::RefCounted<PrefStore>:
   ~PersistentPrefStoreClient() override;
 
  private:
   class InFlightWriteTrie;
   struct InFlightWrite;
 
   void QueueWrite(const std::string& key,
@@ skipping 20 matching lines @@
   std::map<std::string, InFlightWriteTrie> in_flight_writes_tries_;
 
   base::WeakPtrFactory<PersistentPrefStoreClient> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(PersistentPrefStoreClient);
 };
 
 }  // namespace prefs
 
 #endif  // SERVICES_PREFERENCES_PUBLIC_CPP_PERSISTENT_PREF_STORE_CLIENT_H_