Move plugins to be stored in HTMLPlugInElement.

third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.cpp

 /*
  * Copyright (C) 2009, 2010, 2011 Apple 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:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 133 matching lines @@
   if (!layoutObject.style()->hasBackground())
     return true;
 
   // Simple background that is contained within the contents rect.
   return contentsRect(layoutObject).contains(backgroundRect(layoutObject));
 }
 
 static WebLayer* platformLayerForPlugin(LayoutObject& layoutObject) {
   if (!layoutObject.isEmbeddedObject())
     return nullptr;
-  FrameViewBase* frameViewBase =
-      toLayoutEmbeddedObject(layoutObject).frameViewBase();
-  if (!frameViewBase || !frameViewBase->isPluginView())
-    return nullptr;
-  return toPluginView(frameViewBase)->platformLayer();
+  PluginView* plugin = toLayoutEmbeddedObject(layoutObject).plugin();
+  return plugin ? plugin->platformLayer() : nullptr;
 }
 
 static inline bool isAcceleratedContents(LayoutObject& layoutObject) {
   return isAcceleratedCanvas(layoutObject) ||
          (layoutObject.isEmbeddedObject() &&
           toLayoutEmbeddedObject(layoutObject)
               .requiresAcceleratedCompositing()) ||
          layoutObject.isVideo();
 }
 
@@ skipping 3329 matching lines @@
   } else if (graphicsLayer == m_decorationOutlineLayer.get()) {
     name = "Decoration Layer";
   } else {
     ASSERT_NOT_REACHED();
   }
 
   return name;
 }
 
 }  // namespace blink