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

chrome/browser/views/autocomplete/autocomplete_popup_contents_view.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_contents_view.h"
 
 #include "app/gfx/canvas.h"
 #include "app/gfx/color_utils.h"
 #include "app/gfx/insets.h"
 #include "app/gfx/path.h"
@@ skipping 573 matching lines @@
     const BubblePositioner* bubble_positioner)
 #if defined(OS_WIN)
     : popup_(new AutocompletePopupWin(this)),
 #else
     : popup_(new AutocompletePopupGtk(this)),
 #endif
       model_(new AutocompletePopupModel(this, edit_model, profile)),
       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;
   bubble_border_ = bubble_border;
   set_border(bubble_border);
 }
 
 gfx::Rect AutocompletePopupContentsView::GetPopupBounds() const {
   if (!size_animation_.IsAnimating())
     return target_bounds_;
 
   gfx::Rect current_frame_bounds = start_bounds_;
   int total_height_delta = target_bounds_.height() - start_bounds_.height();
   // Round |current_height_delta| instead of truncating so we won't leave single
   // white pixels at the bottom of the popup as long when animating very small
   // height differences.
   int current_height_delta = static_cast<int>(
       size_animation_.GetCurrentValue() * total_height_delta - 0.5);
   current_frame_bounds.set_height(
       current_frame_bounds.height() + current_height_delta);
   return current_frame_bounds;
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 // 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) {
   GetChildViewAt(static_cast<int>(line))->SchedulePaint();
 }
 
 void AutocompletePopupContentsView::UpdatePopupAppearance() {
   if (model_->result().empty()) {
     // No matches, close any existing popup.
     if (popup_->IsCreated()) {
       size_animation_.Stop();
       popup_->Hide();
     }
+    is_open_ = false;
     return;
   }
 
   // Update the match cached by each row, in the process of doing so make sure
   // we have enough row views.
   int total_child_height = 0;
   size_t child_view_count = GetChildViewCount();
   for (size_t i = 0; i < model_->result().size(); ++i) {
     AutocompleteResultView* result_view;
     if (i >= child_view_count) {
@@ skipping 28 matching lines @@
     // appearing for the first time) since that would make the popup feel less
     // responsive.
     GetWidget()->GetBounds(&start_bounds_, true);
     if (popup_->IsVisible() &&
         (target_bounds_.height() < start_bounds_.height()))
       size_animation_.Show();
     else
       start_bounds_ = target_bounds_;
     popup_->Show();
   }
+  is_open_ = true;
 
   SchedulePaint();
 }
 
 void AutocompletePopupContentsView::PaintUpdatesNow() {
   // TODO(beng): remove this from the interface.
 }
 
 AutocompletePopupModel* AutocompletePopupContentsView::GetModel() {
   return model_.get();
@@ skipping 36 matching lines @@
                                                     bool revert_to_default) {
   if (HasMatchAt(index))
     model_->SetSelectedLine(index, revert_to_default);
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 // AutocompletePopupContentsView, AnimationDelegate implementation:
 
 void AutocompletePopupContentsView::AnimationProgressed(
     const Animation* animation) {
   popup_->Show();

[sky, 2009/11/04 00:27:47]

Do you need to set is_open_ here?

[Peter Kasting, 2009/11/04 00:59:58]

No; this should only be called when the popup is already open.  I added a
CHECK() to that effect.

 }
 
 ////////////////////////////////////////////////////////////////////////////////
 // AutocompletePopupContentsView, views::View overrides:
 
 void AutocompletePopupContentsView::Paint(gfx::Canvas* canvas) {
   // We paint our children in an unconventional way.
   //
   // Because the border of this view creates an anti-aliased round-rect region
   // for the contents, we need to render our rectangular result child views into
@@ skipping 117 matching lines @@
 // static
 AutocompletePopupView* AutocompletePopupView::CreatePopupView(
     const gfx::Font& font,
     AutocompleteEditView* edit_view,
     AutocompleteEditModel* edit_model,
     Profile* profile,
     const BubblePositioner* bubble_positioner) {
   return new AutocompletePopupContentsView(font, edit_view, edit_model,
                                            profile, bubble_positioner);
 }