gtk: Use gtk_dialog_get_content_area() throughout.

remoting/host/continue_window_linux.cc

 // Copyright (c) 2011 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 "remoting/host/continue_window.h"
 
 #include <gtk/gtk.h>
 
 #include "base/compiler_specific.h"
 #include "base/logging.h"
@@ skipping 44 matching lines @@
                                   GTK_RESPONSE_OK);
   gtk_window_set_resizable(GTK_WINDOW(continue_window_), FALSE);
 
   // Set always-on-top, otherwise this window tends to be obscured by the
   // DisconnectWindow.
   gtk_window_set_keep_above(GTK_WINDOW(continue_window_), TRUE);
 
   g_signal_connect(continue_window_, "response",
                    G_CALLBACK(OnResponseThunk), this);
 
-  GtkWidget* content_area = GTK_DIALOG(continue_window_)->vbox;
+  GtkWidget* content_area =
+      gtk_dialog_get_content_area(GTK_DIALOG(continue_window_));
 
   GtkWidget* text_label = gtk_label_new(kMessage);
   gtk_label_set_line_wrap(GTK_LABEL(text_label), TRUE);
   // TODO(lambroslambrou): Fix magic numbers, as in disconnect_window_linux.cc.
   gtk_misc_set_padding(GTK_MISC(text_label), 12, 12);
   gtk_container_add(GTK_CONTAINER(content_area), text_label);
 
   gtk_widget_show_all(content_area);
 }
 
@@ skipping 18 matching lines @@
     host_->Shutdown(NULL);
   }
   Hide();
 }
 
 ContinueWindow* ContinueWindow::Create() {
   return new ContinueWindowLinux();
 }
 
 }  // namespace remoting