Store a stacktrace of PrefService destruction in PrefChangeRegistrar

base/prefs/pref_member.h

Index: base/prefs/pref_member.h
diff --git a/base/prefs/pref_member.h b/base/prefs/pref_member.h
index 17f5b447eb4a6f3a1f58985b6e7be0b7dc718c5c..2c2e8e6492b49e8b4ab443a8c4699d0045eaf9d3 100644
--- a/base/prefs/pref_member.h
+++ b/base/prefs/pref_member.h
@@ -117,6 +117,9 @@ class BASE_PREFS_EXPORT PrefMemberBase : public PrefObserver {
   // PrefObserver
   virtual void OnPreferenceChanged(PrefService* service,
                                    const std::string& pref_name) OVERRIDE;
+  // TODO(battre): Remove function (debugging tool for crbug.com/373435).
+  virtual void SetPrefServiceDestructionTrace(
+      const std::string& stack_trace) OVERRIDE;
 
   void VerifyValuePrefName() const {
     DCHECK(!pref_name_.empty());
@@ -144,6 +147,8 @@ class BASE_PREFS_EXPORT PrefMemberBase : public PrefObserver {
   std::string pref_name_;
   NamedChangeCallback observer_;
   PrefService* prefs_;
+  // TODO(battre): Remove attribute (debugging tool for crbug.com/373435).
+  std::string pref_service_destruction_;
 
  protected:
   bool setting_value_;