Gtk3 ui: Add libgtk3ui as a separate build component

chrome/browser/ui/libgtkui/print_dialog_gtk2.h

 // Copyright 2014 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.
 
-#ifndef CHROME_BROWSER_UI_LIBGTK2UI_PRINT_DIALOG_GTK2_H_
-#define CHROME_BROWSER_UI_LIBGTK2UI_PRINT_DIALOG_GTK2_H_
+#ifndef CHROME_BROWSER_UI_LIBGTKUI_PRINT_DIALOG_GTK2_H_
+#define CHROME_BROWSER_UI_LIBGTKUI_PRINT_DIALOG_GTK2_H_
 
 #include <gtk/gtk.h>
 #include <gtk/gtkunixprint.h>
 
 #include "base/compiler_specific.h"
 #include "base/files/file_path.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/sequenced_task_runner_helpers.h"
-#include "chrome/browser/ui/libgtk2ui/gtk2_signal.h"
+#include "chrome/browser/ui/libgtkui/gtk2_signal.h"
 #include "content/public/browser/browser_thread.h"
 #include "printing/print_dialog_gtk_interface.h"
 #include "printing/printing_context_linux.h"
 #include "ui/aura/window_observer.h"
 
 namespace printing {
 class MetafilePlayer;
 class PrintSettings;
 }
 
@@ skipping 55 matching lines @@
   GtkWidget* dialog_;
   GtkPrintSettings* gtk_settings_;
   GtkPageSetup* page_setup_;
   GtkPrinter* printer_;
 
   base::FilePath path_to_pdf_;
 
   DISALLOW_COPY_AND_ASSIGN(PrintDialogGtk2);
 };
 
-#endif  // CHROME_BROWSER_UI_LIBGTK2UI_PRINT_DIALOG_GTK2_H_
+#endif  // CHROME_BROWSER_UI_LIBGTKUI_PRINT_DIALOG_GTK2_H_