Add a setting to disable threaded scrolling

Source/web/WebSettingsImpl.cpp

 /*
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 448 matching lines @@
 void WebSettingsImpl::setEditingBehavior(EditingBehavior behavior)
 {
     m_settings->setEditingBehaviorType(static_cast<EditingBehaviorType>(behavior));
 }
 
 void WebSettingsImpl::setAcceleratedCompositingEnabled(bool enabled)
 {
     m_settings->setAcceleratedCompositingEnabled(enabled);
 }
 
+void WebSettingsImpl::setAcceleratedScrollingEnabled(bool enabled)
+{
+    m_settings->setAcceleratedScrollingEnabled(enabled);
+}
+
 void WebSettingsImpl::setMockScrollbarsEnabled(bool enabled)
 {
     m_settings->setMockScrollbarsEnabled(enabled);
 }
 
 void WebSettingsImpl::setMockGestureTapHighlightsEnabled(bool enabled)
 {
     m_settings->setMockGestureTapHighlightsEnabled(enabled);
 }
 
@@ skipping 242 matching lines @@
 {
     m_settings->setDisallowFullscreenForNonMediaElements(enabled);
 }
 
 void WebSettingsImpl::setV8CacheOptions(V8CacheOptions options)
 {
     m_settings->setV8CacheOptions(static_cast<blink::V8CacheOptions>(options));
 }
 
 } // namespace blink