Fixes possible crash if the window hosting a menu was closed while the

views/widget/widget_gtk.cc

 // Copyright (c) 2010 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 "views/widget/widget_gtk.h"
 
 #include <gdk/gdk.h>
 #include <gdk/gdkx.h>
 #include <X11/extensions/shape.h>
 
@@ skipping 971 matching lines @@
                                        GdkEventVisibility* event) {
   return false;
 }
 
 gboolean WidgetGtk::OnGrabBrokeEvent(GtkWidget* widget, GdkEvent* event) {
   HandleGrabBroke();
   return false;  // To let other widgets get the event.
 }
 
 void WidgetGtk::OnGrabNotify(GtkWidget* widget, gboolean was_grabbed) {
+  if (!window_contents_)
+    return;  // Grab broke after window destroyed, don't try processing it.
+
   gtk_grab_remove(window_contents_);
   HandleGrabBroke();
 }
 
 void WidgetGtk::OnDestroy(GtkWidget* object) {
   // Note that this handler is hooked to GtkObject::destroy.
   widget_ = window_contents_ = NULL;
   if (delete_on_destroy_) {
     // Delays the deletion of this WidgetGtk as we want its children to have
     // access to it when destroyed.
@@ skipping 367 matching lines @@
 
 // static
 Widget* Widget::GetWidgetFromNativeWindow(gfx::NativeWindow native_window) {
   gpointer raw_widget = g_object_get_data(G_OBJECT(native_window), kWidgetKey);
   if (raw_widget)
     return reinterpret_cast<Widget*>(raw_widget);
   return NULL;
 }
 
 }  // namespace views