add support for forcing compositing mode

webkit/glue/webpreferences.h

Index: webkit/glue/webpreferences.h
diff --git a/webkit/glue/webpreferences.h b/webkit/glue/webpreferences.h
index 0d37d395e9c8509311d22a9a88ebf8f8b8cd8c80..c3735043075ef3cc3241a961e2a22aebdb2d708b 100644
--- a/webkit/glue/webpreferences.h
+++ b/webkit/glue/webpreferences.h
@@ -1,4 +1,4 @@
-// Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
+// Copyright (c) 2011 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.
 //
@@ -74,6 +74,7 @@ struct WebPreferences {
   bool show_fps_counter;
   bool asynchronous_spell_checking_enabled;
   bool accelerated_compositing_enabled;
+  bool force_compositing_mode;
   bool composite_to_texture_enabled;
   bool accelerated_layers_enabled;
   bool accelerated_video_enabled;