Add initial GTK web accessibility framework (third attempt).

ui/gfx/gtk_preserve_window.h

Index: ui/gfx/gtk_preserve_window.h
===================================================================
--- ui/gfx/gtk_preserve_window.h	(revision 135807)
+++ ui/gfx/gtk_preserve_window.h	(working copy)
@@ -1,4 +1,4 @@
-// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// 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.
 
@@ -6,6 +6,7 @@
 #define UI_GFX_GTK_PRESERVE_WINDOW_H_
 #pragma once
 
+#include <atk/atk.h>
 #include <gdk/gdk.h>
 #include <gtk/gtk.h>
 
@@ -61,6 +62,14 @@
 UI_EXPORT void gtk_preserve_window_delegate_resize(GtkPreserveWindow* widget,
                                                    gboolean delegate);
 
+// Provide a function to return an AtkObject* when calls to get_accessible
+// are made on this widget. The parameter |userdata| will be passed to the
+// factory function.
+void gtk_preserve_window_set_accessible_factory(
+    GtkPreserveWindow* widget,
+    AtkObject* (*factory)(void* userdata),
+    gpointer userdata);
+
 G_END_DECLS
 
 #endif  // UI_GFX_GTK_PRESERVE_WINDOW_H_