Call ShowRootWindow on NativeWindow's RootWindow to display the window.

content/shell/shell_gtk.cc

 // Copyright (c) 2012 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 "content/shell/shell.h"
 
 #include <gdk/gdkkeysyms.h>
 #include <gtk/gtk.h>
 
 #include "base/logging.h"
@@ skipping 36 matching lines @@
 GtkWidget* CreateMenuBar(Shell* shell) {
   GtkWidget* menu_bar = gtk_menu_bar_new();
   GtkWidget* debug_menu = CreateMenu(menu_bar, "Debug");
   AddMenuEntry(debug_menu, "Show web inspector...",
                G_CALLBACK(ShowWebInspectorActivated), shell);
   return menu_bar;
 }
 
 }  // namespace
 
-void Shell::PlatformInitialize() {
+void Shell::PlatformInitialize(const gfx::Size& default_window_size) {
 }
 
 void Shell::PlatformCleanUp() {
   // Nothing to clean up; GTK will clean up the widgets shortly after.
 }
 
 void Shell::PlatformEnableUIControl(UIControl control, bool is_enabled) {
   if (headless_)
     return;
 
@@ skipping 221 matching lines @@
 
 void Shell::PlatformSetTitle(const string16& title) {
   if (headless_)
     return;
 
   std::string title_utf8 = UTF16ToUTF8(title);
   gtk_window_set_title(GTK_WINDOW(window_), title_utf8.c_str());
 }
 
 }  // namespace content