Try to add more sanity checking to help track down a crash....

chrome/browser/views/autocomplete/autocomplete_popup_win.cc

 // Copyright (c) 2009 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 "chrome/browser/views/autocomplete/autocomplete_popup_win.h"
 
 #include "app/gfx/insets.h"
 #include "app/win_util.h"
 #include "chrome/browser/autocomplete/autocomplete_edit_view_win.h"
 #include "chrome/browser/autocomplete/autocomplete_popup_model.h"
 #include "chrome/browser/views/autocomplete/autocomplete_popup_contents_view.h"
 
 ////////////////////////////////////////////////////////////////////////////////
 // AutocompletePopupWin, public:
 
 AutocompletePopupWin::AutocompletePopupWin(
     AutocompletePopupContentsView* contents)
-    : contents_(contents) {
+    : contents_(contents),
+      is_open_(false) {
   set_delete_on_destroy(false);
   set_window_style(WS_POPUP | WS_CLIPCHILDREN);
   set_window_ex_style(WS_EX_TOOLWINDOW | WS_EX_LAYERED);
 }
 
 AutocompletePopupWin::~AutocompletePopupWin() {
 }
 
+void AutocompletePopupWin::Show() {
+  // Move the popup to the place appropriate for the window's current position -
+  // it may have been moved since it was last shown.
+  SetBounds(contents_->GetPopupBounds());
+  WidgetWin::Show();
+  is_open_ = true;
+}
+
+void AutocompletePopupWin::Hide() {
+  WidgetWin::Hide();
+  is_open_ = false;
+}
+
 void AutocompletePopupWin::Init(AutocompleteEditView* edit_view,
                                 views::View* contents) {
   // Create the popup
   WidgetWin::Init(GetAncestor(edit_view->GetNativeView(), GA_ROOT),
                   contents_->GetPopupBounds());
   // The contents is owned by the LocationBarView.
   contents_->SetParentOwned(false);
   SetContentsView(contents_);
 
   // When an IME is attached to the rich-edit control, retrieve its window
   // handle and show this popup window under the IME windows.
   // Otherwise, show this popup window under top-most windows.
   // TODO(hbono): http://b/1111369 if we exclude this popup window from the
   // display area of IME windows, this workaround becomes unnecessary.
   HWND ime_window = ImmGetDefaultIMEWnd(edit_view->GetNativeView());
   SetWindowPos(ime_window ? ime_window : HWND_NOTOPMOST, 0, 0, 0, 0,
                SWP_NOSIZE | SWP_NOMOVE | SWP_NOACTIVATE | SWP_SHOWWINDOW);
-}
-
-void AutocompletePopupWin::Show() {
-  // Move the popup to the place appropriate for the window's current position -
-  // it may have been moved since it was last shown.
-  SetBounds(contents_->GetPopupBounds());
-  if (!IsVisible())
-    WidgetWin::Show();
+  is_open_ = true;
 }
 
 bool AutocompletePopupWin::IsOpen() const {
-  return IsCreated() && IsVisible();
+  const bool is_open = IsCreated() && IsVisible();
+  CHECK(is_open == is_open_);
+  return is_open;
 }
 
 bool AutocompletePopupWin::IsCreated() const {
   return !!IsWindow();
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 // AutocompletePopupWin, WidgetWin overrides:
 
 LRESULT AutocompletePopupWin::OnMouseActivate(HWND window, UINT hit_test,
                                               UINT mouse_message) {
   return MA_NOACTIVATE;
 }