Fix a use after free crasher in the BrowserAccessibilityManagerWinTest.TestAccessibleHWND test.

content/browser/accessibility/browser_accessibility_win_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 "base/memory/scoped_ptr.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/win/scoped_bstr.h"
 #include "base/win/scoped_comptr.h"
 #include "base/win/scoped_variant.h"
 #include "content/browser/accessibility/browser_accessibility_manager.h"
@@ skipping 726 matching lines @@
   // new parent_hwnd with the right window class to fool older screen
   // readers.
   BrowserAccessibilityStateImpl::GetInstance()->OnScreenReaderDetected();
   manager->MaybeCallNotifyWinEvent(0, 0);
   HWND new_parent_hwnd = manager->parent_hwnd();
   ASSERT_NE(desktop_hwnd, new_parent_hwnd);
   WCHAR hwnd_class_name[256];
   ASSERT_NE(0, GetClassName(new_parent_hwnd, hwnd_class_name, 256));
   ASSERT_STREQ(L"Chrome_RenderWidgetHostHWND", hwnd_class_name);
 
-  // Destroy the hwnd explicitly; that should trigger clearing parent_hwnd().
-  DestroyWindow(new_parent_hwnd);
+  // Destroy the TestLegacyRenderWidgetHostHWND instance. That should in turn
+  // destroy the hwnd, which should clear the parent_hwnd().
+  accessibility_test.reset(NULL);
+  ASSERT_EQ(FALSE, ::IsWindow(new_parent_hwnd));
   ASSERT_EQ(NULL, manager->parent_hwnd());
 
   // Now create it again.
   accessibility_test.reset(new TestLegacyRenderWidgetHostHWND);
   EXPECT_EQ(accessibility_test->Initialize(::GetDesktopWindow()), true);
   manager.reset(
       new BrowserAccessibilityManagerWin(
           accessibility_test->accessible_hwnd(),
           desktop_hwnd_iaccessible,
           BrowserAccessibilityManagerWin::GetEmptyDocument(),
           NULL));
   manager->MaybeCallNotifyWinEvent(0, 0);
   new_parent_hwnd = manager->parent_hwnd();
   ASSERT_FALSE(NULL == new_parent_hwnd);
 
   // This time, destroy the manager first, make sure the AccessibleHWND doesn't
   // crash on destruction (to be caught by SyzyASAN or other tools).
   manager.reset(NULL);
 }
 
 }  // namespace content