chrome: Cleanup class/struct forward declarations

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>
 #include <vector>
 
 #include "base/event_types.h"
 #include "ui/base/ime/linux/text_edit_command_auralinux.h"
 
-namespace content {
-struct NativeWebKeyboardEvent;
-}
-
 namespace ui {
 class Event;
 }
 
 namespace libgtkui {
 
 // This class is a convenience class for handling editor key bindings defined
 // in gtk keyboard theme.
 // In gtk, only GtkEntry and GtkTextView support customizing editor key bindings
 // through keyboard theme. And in gtk keyboard theme definition file, each key
@@ skipping 114 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_