aura: Destroy the compositor before destroying the backing window.

ui/gfx/win/window_impl.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/gfx/win/window_impl.h"
 
 #include <list>
 
 #include "base/debug/alias.h"
 #include "base/memory/singleton.h"
@@ skipping 208 matching lines @@
   CHECK_EQ(this, GetWindowUserData(hwnd));
 }
 
 HICON WindowImpl::GetDefaultWindowIcon() const {
   return NULL;
 }
 
 LRESULT WindowImpl::OnWndProc(UINT message, WPARAM w_param, LPARAM l_param) {
   LRESULT result = 0;
 
+  HWND hwnd = hwnd_;
+  if (message == WM_NCDESTROY)
+    hwnd_ = NULL;
+
   // Handle the message if it's in our message map; otherwise, let the system
   // handle it.
-  if (!ProcessWindowMessage(hwnd_, message, w_param, l_param, result))
-    result = DefWindowProc(hwnd_, message, w_param, l_param);
+  if (!ProcessWindowMessage(hwnd, message, w_param, l_param, result))
+    result = DefWindowProc(hwnd, message, w_param, l_param);
 
   return result;
 }
 
 void WindowImpl::ClearUserData() {
   if (::IsWindow(hwnd_))
     gfx::SetWindowUserData(hwnd_, NULL);
 }
 
 // static
@@ skipping 20 matching lines @@
   return window->OnWndProc(message, w_param, l_param);
 }
 
 ATOM WindowImpl::GetWindowClassAtom() {
   HICON icon = GetDefaultWindowIcon();
   ClassInfo class_info(initial_class_style(), icon);
   return ClassRegistrar::GetInstance()->RetrieveClassAtom(class_info);
 }
 
 }  // namespace gfx