Delete the PreferenceMACs on profile deletion.

components/prefs/pref_service.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.
 
 // This provides a way to access the application's current preferences.
 
 // Chromium settings and storage represent user-selected preferences and
 // information and MUST not be extracted, overwritten or modified except
 // through Chromium defined APIs.
 
@@ skipping 289 matching lines @@
   //
   // As an example, prefs registration in Chrome is triggered by the
   // functions chrome::RegisterPrefs (for global preferences) and
   // chrome::RegisterProfilePrefs (for user-specific preferences)
   // implemented in chrome/browser/prefs/browser_prefs.cc.
   PrefRegistry* DeprecatedGetPrefRegistry();
 
   // Clears mutable values.
   void ClearMutableValues();
 
+  // Invoked when the store is deleted from disk. Allows this PrefService
+  // to tangentially cleanup data it may have saved outside the store.
+  void OnStoreDeletionFromDisk();
+
  protected:
   // The PrefNotifier handles registering and notifying preference observers.
   // It is created and owned by this PrefService. Subclasses may access it for
   // unit testing.
   std::unique_ptr<PrefNotifierImpl> pref_notifier_;
 
   // The PrefValueStore provides prioritized preference values. It is owned by
   // this PrefService. Subclasses may access it for unit testing.
   std::unique_ptr<PrefValueStore> pref_value_store_;
 
@@ skipping 76 matching lines @@
   // is authoritative with respect to what the types and default values
   // of registered preferences are.
   mutable PreferenceMap prefs_map_;
 
   SEQUENCE_CHECKER(sequence_checker_);
 
   DISALLOW_COPY_AND_ASSIGN(PrefService);
 };
 
 #endif  // COMPONENTS_PREFS_PREF_SERVICE_H_