Gtk3 ui: Add libgtk3ui as a separate build component

chrome/browser/ui/libgtkui/native_theme_gtk2.h

Index: chrome/browser/ui/libgtkui/native_theme_gtk2.h
diff --git a/chrome/browser/ui/libgtk2ui/native_theme_gtk2.h b/chrome/browser/ui/libgtkui/native_theme_gtk2.h
similarity index 88%
rename from chrome/browser/ui/libgtk2ui/native_theme_gtk2.h
rename to chrome/browser/ui/libgtkui/native_theme_gtk2.h
index 042a87e6147acc19c4e1abf3ba01fea66247f3b7..a5e7b2b8fe6e8af7dff405927890787348db60e9 100644
--- a/chrome/browser/ui/libgtk2ui/native_theme_gtk2.h
+++ b/chrome/browser/ui/libgtkui/native_theme_gtk2.h
@@ -2,8 +2,8 @@
 // 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_NATIVE_THEME_GTK2_H_
-#define CHROME_BROWSER_UI_LIBGTK2UI_NATIVE_THEME_GTK2_H_
+#ifndef CHROME_BROWSER_UI_LIBGTKUI_NATIVE_THEME_GTK2_H_
+#define CHROME_BROWSER_UI_LIBGTKUI_NATIVE_THEME_GTK2_H_
 
 #include <gtk/gtk.h>
 
@@ -11,7 +11,7 @@
 #include "ui/native_theme/native_theme_base.h"
 
 
-namespace libgtk2ui {
+namespace libgtkui {
 
 // A version of NativeTheme that uses GTK2 supplied colours instead of the
 // default aura colours. Analogue to NativeThemeWin, except that can't be
@@ -55,6 +55,6 @@ class NativeThemeGtk2 : public ui::NativeThemeBase {
   DISALLOW_COPY_AND_ASSIGN(NativeThemeGtk2);
 };
 
-}  // namespace libgtk2ui
+}  // namespace libgtkui
 
-#endif  // CHROME_BROWSER_UI_LIBGTK2UI_NATIVE_THEME_GTK2_H_
+#endif  // CHROME_BROWSER_UI_LIBGTKUI_NATIVE_THEME_GTK2_H_