Move preference MACs to the protected preference stores.

base/prefs/pref_filter.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 BASE_PREFS_PREF_FILTER_H_
 #define BASE_PREFS_PREF_FILTER_H_
 
 #include <string>
 
 #include "base/callback_forward.h"
@@ skipping 30 matching lines @@
       const PostFilterOnLoadCallback& post_filter_on_load_callback,
       base::DictionaryValue* pref_store_contents) = 0;
 
   // Receives notification when a pref store value is changed, before Observers
   // are notified.
   virtual void FilterUpdate(const std::string& path) = 0;
 
   // Receives notification when the pref store is about to serialize data
   // contained in |pref_store_contents| to a string.
   virtual void FilterSerializeData(
-      const base::DictionaryValue* pref_store_contents) = 0;
+      base::DictionaryValue* pref_store_contents) = 0;
 };
 
 #endif  // BASE_PREFS_PREF_FILTER_H_