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

chrome/browser/views/autocomplete/autocomplete_popup_contents_view.cc

Index: chrome/browser/views/autocomplete/autocomplete_popup_contents_view.cc
===================================================================
--- chrome/browser/views/autocomplete/autocomplete_popup_contents_view.cc	(revision 30836)
+++ chrome/browser/views/autocomplete/autocomplete_popup_contents_view.cc	(working copy)
@@ -591,7 +591,8 @@
       edit_view_(edit_view),
       bubble_positioner_(bubble_positioner),
       result_font_(font.DeriveFont(kEditFontAdjust)),
-      ALLOW_THIS_IN_INITIALIZER_LIST(size_animation_(this)) {
+      ALLOW_THIS_IN_INITIALIZER_LIST(size_animation_(this)),
+      is_open_(false) {
   // The following little dance is required because set_border() requires a
   // pointer to a non-const object.
   BubbleBorder* bubble_border = new BubbleBorder;
@@ -619,7 +620,9 @@
 // AutocompletePopupContentsView, AutocompletePopupView overrides:
 
 bool AutocompletePopupContentsView::IsOpen() const {
-  return popup_->IsOpen();
+  const bool is_open = popup_->IsOpen();
+  CHECK(is_open == is_open_);
+  return is_open;
 }
 
 void AutocompletePopupContentsView::InvalidateLine(size_t line) {
@@ -633,6 +636,7 @@
       size_animation_.Stop();
       popup_->Hide();
     }
+    is_open_ = false;
     return;
   }
 
@@ -681,6 +685,7 @@
       start_bounds_ = target_bounds_;
     popup_->Show();
   }
+  is_open_ = true;
 
   SchedulePaint();
 }