Adds back some debugging code

ui/aura/window_observer.h

Index: ui/aura/window_observer.h
diff --git a/ui/aura/window_observer.h b/ui/aura/window_observer.h
index 926e5c4428a5b25a9ad09b0ae3f713a927b3cb25..ef1259a234d5b99d8e1dd80e3ed51b85fd8c2ff4 100644
--- a/ui/aura/window_observer.h
+++ b/ui/aura/window_observer.h
@@ -31,6 +31,8 @@ class AURA_EXPORT WindowObserver {
     Window* receiver;   // The window receiving the notification.
   };
 
+  WindowObserver();
+
   // Called when a window is added or removed. Notifications are sent to the
   // following hierarchies in this order:
   // 1. |target|.
@@ -111,7 +113,22 @@ class AURA_EXPORT WindowObserver {
                                               Window* new_root) {}
 
  protected:
-  virtual ~WindowObserver() {}
+  virtual ~WindowObserver();
+
+ private:
+  friend class Window;
+
+  // Called when this is added as an observer on |window|.
+  void OnObservingWindow(Window* window);
+
+  // Called when this is removed from the observers on |window|.
+  void OnUnobservingWindow(Window* window);
+
+  // Tracks the number of windows being observed to track down
+  // http://crbug.com/365364.
+  int observing_;
+
+  DISALLOW_COPY_AND_ASSIGN(WindowObserver);
 };
 
 }  // namespace aura