Make sure WindowObservers are removed from window before destruction

ash/wm/resize_shadow_controller.cc

 // Copyright (c) 2012 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 "ash/wm/resize_shadow_controller.h"
 
 #include <utility>
 
 #include "ash/wm/resize_shadow.h"
 #include "ui/aura/window.h"
@@ skipping 33 matching lines @@
     aura::Window* window,
     const gfx::Rect& old_bounds,
     const gfx::Rect& new_bounds) {
   ResizeShadow* shadow = GetShadowForWindow(window);
   if (shadow)
     shadow->Layout(new_bounds);
 }
 
 void ResizeShadowController::OnWindowDestroyed(aura::Window* window) {
   window_shadows_.erase(window);
+  aura::WindowObserver::OnWindowDestroyed(window);
 }
 
 ResizeShadow* ResizeShadowController::CreateShadow(aura::Window* window) {
   linked_ptr<ResizeShadow> shadow(new ResizeShadow());
   window_shadows_.insert(std::make_pair(window, shadow));
   // Attach the layers to this window.
   shadow->Init(window);
   // Ensure initial bounds are correct.
   shadow->Layout(window->bounds());
   // Watch for bounds changes.
   window->AddObserver(this);
   return shadow.get();
 }
 
 ResizeShadow* ResizeShadowController::GetShadowForWindow(aura::Window* window) {
   WindowShadowMap::const_iterator it = window_shadows_.find(window);
   return it != window_shadows_.end() ? it->second.get() : NULL;
 }
 
 }  // namespace internal
 }  // namespace ash