Be able to print items that do window.print(); window.close() (airline tix e.g.)

chrome/browser/prefs/pref_notifier_impl.cc

Index: chrome/browser/prefs/pref_notifier_impl.cc
diff --git a/chrome/browser/prefs/pref_notifier_impl.cc b/chrome/browser/prefs/pref_notifier_impl.cc
index 2dd454f948092ed223eeaf2916302ae64ff8a561..bf44dede42aad2191f0b2ab0cb534e24c08d7ba3 100644
--- a/chrome/browser/prefs/pref_notifier_impl.cc
+++ b/chrome/browser/prefs/pref_notifier_impl.cc
@@ -4,6 +4,7 @@
 
 #include "chrome/browser/prefs/pref_notifier_impl.h"
 
+#include "base/debug/stack_trace.h"
 #include "base/stl_util.h"
 #include "chrome/browser/prefs/pref_service.h"
 #include "chrome/common/chrome_notification_types.h"
@@ -17,11 +18,16 @@ PrefNotifierImpl::PrefNotifierImpl(PrefService* service)
 PrefNotifierImpl::~PrefNotifierImpl() {
   DCHECK(CalledOnValidThread());
 
+  bool already_printed_stacktrace = false;
   // Verify that there are no pref observers when we shut down.
   for (PrefObserverMap::iterator it = pref_observers_.begin();
        it != pref_observers_.end(); ++it) {
     NotificationObserverList::Iterator obs_iterator(*(it->second));
     if (obs_iterator.GetNext()) {
+      if (!already_printed_stacktrace) {
+        already_printed_stacktrace = true;
+        base::debug::StackTrace().PrintBacktrace();
+      }
       LOG(WARNING) << "pref observer found at shutdown " << it->first;
     }
   }