Make sure WindowObservers are removed from window before destruction

ui/aura/client/default_activation_client.cc

 // Copyright 2013 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 "ui/aura/client/default_activation_client.h"
 
 #include "ui/aura/client/activation_change_observer.h"
 #include "ui/aura/client/activation_delegate.h"
 #include "ui/aura/window.h"
 
@@ skipping 84 matching lines @@
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 // DefaultActivationClient, WindowObserver implementation:
 
 void DefaultActivationClient::OnWindowDestroyed(Window* window) {
   if (window == last_active_)
     last_active_ = NULL;
 
   if (window == GetActiveWindow()) {
-    window->RemoveObserver(this);
     active_windows_.pop_back();
     Window* next_active = GetActiveWindow();
     if (next_active && aura::client::GetActivationChangeObserver(next_active)) {
       aura::client::GetActivationChangeObserver(next_active)->OnWindowActivated(
           next_active, NULL);
     }
     return;
   }
 
   RemoveActiveWindow(window);
 }
 
 void DefaultActivationClient::RemoveActiveWindow(Window* window) {
   for (unsigned int i = 0; i < active_windows_.size(); ++i) {
     if (active_windows_[i] == window) {
       active_windows_.erase(active_windows_.begin() + i);
       window->RemoveObserver(this);
       return;
     }
   }
 }
 
 }  // namespace client
 }  // namespace aura