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

chrome/browser/views/autocomplete/autocomplete_popup_win.cc

Index: chrome/browser/views/autocomplete/autocomplete_popup_win.cc
===================================================================
--- chrome/browser/views/autocomplete/autocomplete_popup_win.cc	(revision 30836)
+++ chrome/browser/views/autocomplete/autocomplete_popup_win.cc	(working copy)
@@ -15,7 +15,8 @@
 
 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);
@@ -24,6 +25,19 @@
 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
@@ -41,18 +55,13 @@
   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);
+  is_open_ = true;
 }
 
-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();
-}
-
 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 {