Make sure WindowObservers are removed from window before destruction

ui/aura/window_unittest.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 "ui/aura/window.h"
 
 #include <string>
 #include <utility>
 #include <vector>
 
@@ skipping 1939 matching lines @@
   virtual void OnWindowVisibilityChanged(Window* window,
                                          bool visible) OVERRIDE {
     visibility_info_.reset(new VisibilityInfo);
     visibility_info_->window_visible = window->IsVisible();
     visibility_info_->visible_param = visible;
   }
 
   virtual void OnWindowDestroyed(Window* window) OVERRIDE {
     EXPECT_FALSE(window->parent());
     destroyed_count_++;
+    aura::WindowObserver::OnWindowDestroyed(window);
   }
 
   virtual void OnWindowPropertyChanged(Window* window,
                                        const void* key,
                                        intptr_t old) OVERRIDE {
     property_key_ = key;
     old_property_value_ = old;
   }
 
   int added_count_;
@@ skipping 1391 matching lines @@
 
   w111->SetBounds(gfx::Rect(7, 8, 11, 12));
   EXPECT_EQ("7,8 11x12", w111->bounds().ToString());
   EXPECT_EQ("7,8 11x12", w111->layer()->bounds().ToString());
 
   delete w1ll;
 }
 
 }  // namespace test
 }  // namespace aura