Implement window.alert() and its cousins for extensions....

chrome/browser/app_modal_dialog_gtk.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/app_modal_dialog.h"
 
 #include <gtk/gtk.h>
 
 #include "app/l10n_util.h"
 #include "app/message_box_flags.h"
@@ skipping 104 matching lines @@
   // We want the alert to be app modal so put all the browser windows into the
   // same window group.
   GtkWindowGroup* window_group = gtk_window_group_new();
   for (BrowserList::const_iterator it = BrowserList::begin();
        it != BrowserList::end(); ++it) {
     BrowserWindowGtk* window = static_cast<BrowserWindowGtk*>((*it)->window());
     gtk_window_group_add_window(window_group, window->window());
   }
   g_object_unref(window_group);
 
-  GtkWindow* window = tab_contents_->view()->GetTopLevelNativeWindow();
+  gfx::NativeWindow window = client_->GetMessageBoxRootWindow();
   dialog_ = gtk_message_dialog_new(window, GTK_DIALOG_MODAL,
       message_type, buttons, "%s", WideToUTF8(message_text_).c_str());
   gtk_window_set_title(GTK_WINDOW(dialog_), WideToUTF8(title_).c_str());
 
   // Adjust content area as needed.  Set up the prompt text entry or
   // suppression check box.
   if (MessageBoxFlags::kIsJavascriptPrompt == dialog_flags_) {
     // TODO(tc): Replace with gtk_dialog_get_content_area() when using GTK 2.14+
     GtkWidget* contents_vbox = GTK_DIALOG(dialog_)->vbox;
     GtkWidget* text_box = gtk_entry_new();
@@ skipping 64 matching lines @@
   }
 }
 
 void AppModalDialog::AcceptWindow() {
   OnDialogResponse(GTK_DIALOG(dialog_), GTK_RESPONSE_OK, this);
 }
 
 void AppModalDialog::CancelWindow() {
   OnDialogResponse(GTK_DIALOG(dialog_), GTK_RESPONSE_CANCEL, this);
 }