Delete the PreferenceMACs on profile deletion.

components/prefs/persistent_pref_store.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 COMPONENTS_PREFS_PERSISTENT_PREF_STORE_H_
 #define COMPONENTS_PREFS_PERSISTENT_PREF_STORE_H_
 
 #include <string>
 
 #include "base/callback.h"
@@ skipping 61 matching lines @@
 
   // Schedule a write if there is any lossy data pending. Unlike
   // CommitPendingWrite() this does not immediately sync to disk, instead it
   // triggers an eventual write if there is lossy data pending and if there
   // isn't one scheduled already.
   virtual void SchedulePendingLossyWrites() = 0;
 
   // It should be called only for Incognito pref store.
   virtual void ClearMutableValues() = 0;
 
+  // Cleans preference data that may have been saved outside of the store.
+  virtual void OnStoreDeletionFromDisk() = 0;
+
  protected:
   ~PersistentPrefStore() override {}
 };
 
 #endif  // COMPONENTS_PREFS_PERSISTENT_PREF_STORE_H_