Store a stacktrace of PrefService destruction in PrefChangeRegistrar

base/prefs/pref_notifier_impl.h

 // Copyright (c) 2011 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_NOTIFIER_IMPL_H_
 #define BASE_PREFS_PREF_NOTIFIER_IMPL_H_
 
 #include <list>
 #include <string>
 
@@ skipping 25 matching lines @@
   // parameter will be set to true for successful initialization,
   // false for unsuccessful.
   void AddInitObserver(base::Callback<void(bool)> observer);
 
   void SetPrefService(PrefService* pref_service);
 
  protected:
   // PrefNotifier overrides.
   virtual void OnPreferenceChanged(const std::string& pref_name) OVERRIDE;
   virtual void OnInitializationCompleted(bool succeeded) OVERRIDE;
+  // TODO(battre): Delete this. See crbug.com/373435.
+  virtual void BroadcastPrefServiceDestructionTrace(
+      const std::string& stack_trace) OVERRIDE;
 
   // A map from pref names to a list of observers. Observers get fired in the
   // order they are added. These should only be accessed externally for unit
   // testing.
   typedef ObserverList<PrefObserver> PrefObserverList;
   typedef base::hash_map<std::string, PrefObserverList*> PrefObserverMap;
 
   typedef std::list<base::Callback<void(bool)> > PrefInitObserverList;
 
   const PrefObserverMap* pref_observers() const { return &pref_observers_; }
 
  private:
   // For the given pref_name, fire any observer of the pref. Virtual so it can
   // be mocked for unit testing.
   virtual void FireObservers(const std::string& path);
 
   // Weak reference; the notifier is owned by the PrefService.
   PrefService* pref_service_;
 
   PrefObserverMap pref_observers_;
   PrefInitObserverList init_observers_;
 
   base::ThreadChecker thread_checker_;
 
   DISALLOW_COPY_AND_ASSIGN(PrefNotifierImpl);
 };
 
 #endif  // BASE_PREFS_PREF_NOTIFIER_IMPL_H_