Gtk3 ui: Add libgtk3ui as a separate build component

chrome/browser/ui/libgtkui/gtk2_signal.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.
 
-#ifndef CHROME_BROWSER_UI_LIBGTK2UI_GTK2_SIGNAL_H_
-#define CHROME_BROWSER_UI_LIBGTK2UI_GTK2_SIGNAL_H_
+#ifndef CHROME_BROWSER_UI_LIBGTKUI_GTK2_SIGNAL_H_
+#define CHROME_BROWSER_UI_LIBGTKUI_GTK2_SIGNAL_H_
 
 #include "ui/base/glib/glib_signal.h"
 
 typedef struct _GtkWidget GtkWidget;
 
 // These macros handle the common case where the sender object will be a
 // GtkWidget*.
 #define CHROMEGTK_CALLBACK_0(CLASS, RETURN, METHOD) \
   CHROMEG_CALLBACK_0(CLASS, RETURN, METHOD, GtkWidget*);
 
@@ skipping 41 matching lines @@
 #define CHROMEGTK_VIRTUAL_CALLBACK_5(CLASS, RETURN, METHOD, ARG1, ARG2, ARG3, \
                                      ARG4, ARG5)                              \
   CHROMEG_VIRTUAL_CALLBACK_5(CLASS, RETURN, METHOD, GtkWidget*, ARG1, ARG2,   \
                              ARG3, ARG4, ARG5);
 
 #define CHROMEGTK_VIRTUAL_CALLBACK_6(CLASS, RETURN, METHOD, ARG1, ARG2, ARG3, \
                                      ARG4, ARG5, ARG6)                        \
   CHROMEG_VIRTUAL_CALLBACK_6(CLASS, RETURN, METHOD, GtkWidget*, ARG1, ARG2,   \
                              ARG3, ARG4, ARG5, ARG6);
 
-#endif  // CHROME_BROWSER_UI_LIBGTK2UI_GTK2_SIGNAL_H_
+#endif  // CHROME_BROWSER_UI_LIBGTKUI_GTK2_SIGNAL_H_