Gtk3 ui: Add libgtk3ui as a separate build component

chrome/browser/ui/libgtkui/x11_input_method_context_impl_gtk2.h

 // Copyright 2013 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_X11_INPUT_METHOD_CONTEXT_IMPL_GTK2_H_
-#define CHROME_BROWSER_UI_LIBGTK2UI_X11_INPUT_METHOD_CONTEXT_IMPL_GTK2_H_
+#ifndef CHROME_BROWSER_UI_LIBGTKUI_X11_INPUT_METHOD_CONTEXT_IMPL_GTK2_H_
+#define CHROME_BROWSER_UI_LIBGTKUI_X11_INPUT_METHOD_CONTEXT_IMPL_GTK2_H_
 
 #include <vector>
 
 #include "base/containers/hash_tables.h"
 #include "base/event_types.h"
 #include "base/macros.h"
 #include "base/strings/string16.h"
 #include "ui/base/glib/glib_integers.h"
 #include "ui/base/glib/glib_signal.h"
 #include "ui/base/ime/linux/linux_input_method_context.h"
 #include "ui/gfx/geometry/rect.h"
 
 typedef union _GdkEvent GdkEvent;
 typedef struct _GtkIMContext GtkIMContext;
 
-namespace libgtk2ui {
+namespace libgtkui {
 
 // An implementation of LinuxInputMethodContext which is based on X11 event loop
 // and uses GtkIMContext(gtk-immodule) as a bridge from/to underlying IMEs.
 class X11InputMethodContextImplGtk2 : public ui::LinuxInputMethodContext {
  public:
   X11InputMethodContextImplGtk2(ui::LinuxInputMethodContextDelegate* delegate,
                                 bool is_simple);
   ~X11InputMethodContextImplGtk2() override;
 
   // Overriden from ui::LinuxInputMethodContext
@@ skipping 49 matching lines @@
   base::hash_set<unsigned int> modifier_keycodes_;
 
   // A list of keycodes of each modifier key.
   std::vector<int> meta_keycodes_;
   std::vector<int> super_keycodes_;
   std::vector<int> hyper_keycodes_;
 
   DISALLOW_COPY_AND_ASSIGN(X11InputMethodContextImplGtk2);
 };
 
-}  // namespace libgtk2ui
+}  // namespace libgtkui
 
-#endif  // CHROME_BROWSER_UI_LIBGTK2UI_X11_INPUT_METHOD_CONTEXT_IMPL_GTK2_H_
+#endif  // CHROME_BROWSER_UI_LIBGTKUI_X11_INPUT_METHOD_CONTEXT_IMPL_GTK2_H_