Clear a preference when sync tries to delete a preference

chrome/browser/prefs/pref_model_associator.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 CHROME_BROWSER_PREFS_PREF_MODEL_ASSOCIATOR_H_
 #define CHROME_BROWSER_PREFS_PREF_MODEL_ASSOCIATOR_H_
 
 #include <map>
 #include <set>
 #include <string>
@@ skipping 74 matching lines @@
       const std::string& name,
       const base::Value& local_value,
       const base::Value& server_value);
 
   // Fills |sync_data| with a sync representation of the preference data
   // provided.
   bool CreatePrefSyncData(const std::string& name,
                           const base::Value& value,
                           syncer::SyncData* sync_data) const;
 
-  // Extract preference value and name from sync specifics.
+  // Extract preference value from sync specifics.
   base::Value* ReadPreferenceSpecifics(
-      const sync_pb::PreferenceSpecifics& specifics,
-      std::string* name);
+      const sync_pb::PreferenceSpecifics& specifics);
 
   // Returns true if the pref under the given name is pulled down from sync.
   // Note this does not refer to SYNCABLE_PREF.
   bool IsPrefSynced(const std::string& name) const;
 
   // Adds a SyncedPrefObserver to watch for changes to a specific pref.
   void AddSyncedPrefObserver(const std::string& name,
                              SyncedPrefObserver* observer);
 
   // Removes a SyncedPrefObserver from a pref's list of observers.
@@ skipping 77 matching lines @@
       SyncedPrefObserverMap;
 
   void NotifySyncedPrefObservers(const std::string& path, bool from_sync) const;
 
   SyncedPrefObserverMap synced_pref_observers_;
 
   DISALLOW_COPY_AND_ASSIGN(PrefModelAssociator);
 };
 
 #endif  // CHROME_BROWSER_PREFS_PREF_MODEL_ASSOCIATOR_H_