Gtk: Change NULL to nullptr

chrome/browser/ui/libgtkui/gtk_key_bindings_handler.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_LIBGTKUI_GTK_KEY_BINDINGS_HANDLER_H_
 #define CHROME_BROWSER_UI_LIBGTKUI_GTK_KEY_BINDINGS_HANDLER_H_
 
 #include <gtk/gtk.h>
 
 #include <string>
@@ skipping 28 matching lines @@
 // See webkit/glue/editor_client_impl.cc for key bindings predefined in our
 // webkit glue.
 class Gtk2KeyBindingsHandler {
  public:
   Gtk2KeyBindingsHandler();
   virtual ~Gtk2KeyBindingsHandler();
 
   // Matches a key event against predefined gtk key bindings, false will be
   // returned if the key event doesn't correspond to a predefined key binding.
   // Edit commands matched with |event| will be stored in |edit_commands|, if
-  // non-NULL.
+  // non-nullptr.
   bool MatchEvent(const ui::Event& event,
                   std::vector<ui::TextEditCommandAuraLinux>* commands);
 
  private:
   // Object structure of Handler class, which is derived from GtkTextView.
   struct Handler {
     GtkTextView parent_object;
     Gtk2KeyBindingsHandler* owner;
   };
 
@@ skipping 80 matching lines @@
   // Buffer to store the match results.
   std::vector<ui::TextEditCommandAuraLinux> edit_commands_;
 
   // Whether the current X server has the XKeyboard extension.
   bool has_xkb_;
 };
 
 }  // namespace libgtkui
 
 #endif  // CHROME_BROWSER_UI_LIBGTKUI_GTK_KEY_BINDINGS_HANDLER_H_