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

chrome/browser/prefs/pref_notifier_impl.cc

 // 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.
 
 #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"
 #include "content/common/notification_observer.h"
 #include "content/common/notification_service.h"
 
 PrefNotifierImpl::PrefNotifierImpl(PrefService* service)
     : pref_service_(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;
     }
   }
 
   STLDeleteContainerPairSecondPointers(pref_observers_.begin(),
                                        pref_observers_.end());
   pref_observers_.clear();
 }
 
 void PrefNotifierImpl::AddPrefObserver(const char* path,
@@ skipping 62 matching lines @@
     return;
 
   NotificationObserverList::Iterator it(*(observer_iterator->second));
   NotificationObserver* observer;
   while ((observer = it.GetNext()) != NULL) {
     observer->Observe(chrome::NOTIFICATION_PREF_CHANGED,
                       Source<PrefService>(pref_service_),
                       Details<const std::string>(&path));
   }
 }