Store a stacktrace of PrefService destruction in PrefChangeRegistrar

base/prefs/pref_change_registrar.h

Index: base/prefs/pref_change_registrar.h
diff --git a/base/prefs/pref_change_registrar.h b/base/prefs/pref_change_registrar.h
index a914bea7d48cec7c4cf2149d7525c54dc10a76b2..84640a9dad4e7b85c946c0dd034cd8952223d3cb 100644
--- a/base/prefs/pref_change_registrar.h
+++ b/base/prefs/pref_change_registrar.h
@@ -66,6 +66,9 @@ class BASE_PREFS_EXPORT PrefChangeRegistrar : public PrefObserver {
   // PrefObserver:
   virtual void OnPreferenceChanged(PrefService* service,
                                    const std::string& pref_name) OVERRIDE;
+  // TODO(battre): Delete function. See crbug.com/373435.
+  virtual void SetPrefServiceDestructionTrace(
+      const std::string& stack_trace) OVERRIDE;
 
   static void InvokeUnnamedCallback(const base::Closure& callback,
                                     const std::string& pref_name);
@@ -74,6 +77,8 @@ class BASE_PREFS_EXPORT PrefChangeRegistrar : public PrefObserver {
 
   ObserverMap observers_;
   PrefService* service_;
+  // TODO(battre): Remove attribute (debugging tool for crbug.com/373435).
+  std::string pref_service_destruction_;
 
   DISALLOW_COPY_AND_ASSIGN(PrefChangeRegistrar);
 };