Make sure WindowObservers are removed from window before destruction

ui/aura/window.cc

Index: ui/aura/window.cc
diff --git a/ui/aura/window.cc b/ui/aura/window.cc
index fcb5ac966eade1a8ed9952c9bb8a7e18c24e8d10..c5dae64c6e568cec7f11122396d44b305ed07f95 100644
--- a/ui/aura/window.cc
+++ b/ui/aura/window.cc
@@ -167,7 +167,12 @@ Window::~Window() {
   // Delegate and observers need to be notified after transients are deleted.
   if (delegate_)
     delegate_->OnWindowDestroyed();
-  FOR_EACH_OBSERVER(WindowObserver, observers_, OnWindowDestroyed(this));
+  ObserverListBase<WindowObserver>::Iterator iter(observers_);
+  WindowObserver* observer;
+  while ((observer = iter.GetNext())) {
+    RemoveObserver(observer);
+    observer->OnWindowDestroyed(this);
+  }
 
   // Clear properties.
   for (std::map<const void*, Value>::const_iterator iter = prop_map_.begin();