Remove mainthread overhang painting code

Source/web/WebPluginContainerImpl.h

 /*
  * Copyright (C) 2009 Google Inc. All rights reserved.
  * Copyright (C) 2014 Opera Software ASA. 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.
@@ skipping 145 matching lines @@
     virtual void didFinishLoading() override;
     virtual void didFailLoading(const ResourceError&) override;
 
     void willDestroyPluginLoadObserver(WebPluginLoadObserver*);
 
     ScrollbarGroup* scrollbarGroup();
 
     void willStartLiveResize();
     void willEndLiveResize();
 
-    bool paintCustomOverhangArea(GraphicsContext*, const IntRect&, const IntRect&, const IntRect&);
-
     DECLARE_VIRTUAL_TRACE();
     virtual void dispose() override;
 
 #if ENABLE(OILPAN)
     virtual LocalFrame* pluginFrame() const override { return frame(); }
     virtual void shouldDisposePlugin() override;
 #endif
 
 private:
     WebPluginContainerImpl(HTMLPlugInElement*, WebPlugin*);
@@ skipping 47 matching lines @@
 };
 
 DEFINE_TYPE_CASTS(WebPluginContainerImpl, Widget, widget, widget->isPluginContainer(), widget.isPluginContainer());
 // Unlike Widget, we need not worry about object type for container.
 // WebPluginContainerImpl is the only subclass of WebPluginContainer.
 DEFINE_TYPE_CASTS(WebPluginContainerImpl, WebPluginContainer, container, true, true);
 
 } // namespace blink
 
 #endif