Always give RenderParts a RenderLayer.

Source/core/rendering/RenderEmbeddedObject.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 2000 Simon Hausmann <hausmann@kde.org>
  *           (C) 2000 Stefan Schimanski (1Stein@gmx.de)
  * Copyright (C) 2004, 2005, 2006, 2008, 2009, 2010 Apple Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
@@ skipping 45 matching lines @@
     : RenderPart(element)
     , m_showsUnavailablePluginIndicator(false)
 {
     view()->frameView()->setIsVisuallyNonEmpty();
 }
 
 RenderEmbeddedObject::~RenderEmbeddedObject()
 {
 }
 
+LayerType RenderEmbeddedObject::layerTypeRequired() const
+{
+    // This can't just use RenderPart::layerTypeRequired, because RenderLayerCompositor
+    // doesn't loop through RenderEmbeddedObjects the way it does frames in order
+    // to update the self painting bit on their RenderLayer.
+    // Also, unlike iframes, embeds don't used the usesCompositing bit on RenderView
+    // in requiresAcceleratedCompositing.
+    if (requiresAcceleratedCompositing())
+        return NormalLayer;
+    return RenderPart::layerTypeRequired();
+}
+
 static String unavailablePluginReplacementText(Node* node, RenderEmbeddedObject::PluginUnavailabilityReason pluginUnavailabilityReason)
 {
     Locale& locale = node ? toElement(node)->locale() : Locale::defaultLocale();
     switch (pluginUnavailabilityReason) {
     case RenderEmbeddedObject::PluginMissing:
         return locale.queryString(blink::WebLocalizedString::MissingPluginText);
     case RenderEmbeddedObject::PluginBlockedByContentSecurityPolicy:
         return locale.queryString(blink::WebLocalizedString::BlockedPluginText);
     }
 
@@ skipping 131 matching lines @@
 }
 
 RenderBox* RenderEmbeddedObject::embeddedContentBox() const
 {
     if (!node() || !widget() || !widget()->isFrameView())
         return 0;
     return toFrameView(widget())->embeddedContentBox();
 }
 
 }