Gtk3 ui: Add libgtk3ui as a separate build component

chrome/browser/ui/libgtkui/select_file_dialog_impl.h

 // 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.
 //
 // This file implements common select dialog functionality between GTK and KDE.
 
-#ifndef CHROME_BROWSER_UI_LIBGTK2UI_SELECT_FILE_DIALOG_IMPL_H_
-#define CHROME_BROWSER_UI_LIBGTK2UI_SELECT_FILE_DIALOG_IMPL_H_
+#ifndef CHROME_BROWSER_UI_LIBGTKUI_SELECT_FILE_DIALOG_IMPL_H_
+#define CHROME_BROWSER_UI_LIBGTKUI_SELECT_FILE_DIALOG_IMPL_H_
 
 #include <stddef.h>
 
 #include <set>
 
 #include "base/compiler_specific.h"
 #include "base/macros.h"
 #include "base/nix/xdg_util.h"
 #include "ui/aura/window.h"
 #include "ui/shell_dialogs/select_file_dialog.h"
 #include "ui/shell_dialogs/select_file_policy.h"
 
-namespace libgtk2ui {
+namespace libgtkui {
 
 // Shared implementation SelectFileDialog used by SelectFileDialogImplGTK
 class SelectFileDialogImpl : public ui::SelectFileDialog {
  public:
   // Main factory method which returns correct type.
   static ui::SelectFileDialog* Create(Listener* listener,
                                       ui::SelectFilePolicy* policy);
 
   // Factory method for creating a GTK-styled SelectFileDialogImpl
   static SelectFileDialogImpl* NewSelectFileDialogImplGTK(
@@ skipping 45 matching lines @@
   Type type_;
 
   // These two variables track where the user last saved a file or opened a
   // file so that we can display future dialogs with the same starting path.
   static base::FilePath* last_saved_path_;
   static base::FilePath* last_opened_path_;
 
   DISALLOW_COPY_AND_ASSIGN(SelectFileDialogImpl);
 };
 
-}  // namespace libgtk2ui
+}  // namespace libgtkui
 
-#endif  // CHROME_BROWSER_UI_LIBGTK2UI_SELECT_FILE_DIALOG_IMPL_H_
+#endif  // CHROME_BROWSER_UI_LIBGTKUI_SELECT_FILE_DIALOG_IMPL_H_