Attach a WebLayer to a frame element for out-of-process iframes.

Source/core/rendering/CompositedLayerMapping.cpp

Index: Source/core/rendering/CompositedLayerMapping.cpp
diff --git a/Source/core/rendering/CompositedLayerMapping.cpp b/Source/core/rendering/CompositedLayerMapping.cpp
index a5ecbffd96fcc5b94fc979a105d97674c365d71a..4b1c50e9606e9c42b2681c7b5e73502dd72d6c38 100644
--- a/Source/core/rendering/CompositedLayerMapping.cpp
+++ b/Source/core/rendering/CompositedLayerMapping.cpp
@@ -504,6 +504,8 @@ bool CompositedLayerMapping::updateGraphicsLayerConfiguration()
     if (renderer->isEmbeddedObject() && toRenderEmbeddedObject(renderer)->allowsAcceleratedCompositing()) {
         PluginView* pluginView = toPluginView(toRenderWidget(renderer)->widget());
         m_graphicsLayer->setContentsToPlatformLayer(pluginView->platformLayer());
+    } else if ((renderer->isRenderIFrame() || renderer->isFrame()) && toHTMLFrameOwnerElement(renderer->node())->contentFrame() && toHTMLFrameOwnerElement(renderer->node())->contentFrame()->platformLayer()) {

[eseidel, 2013/12/11 18:50:01]

Don't we have a frame base class for these both?  Maybe you just want to just
grab the node and see if the node is a  frameOwnerElement directly?

[kenrb, 2013/12/11 22:44:56]

The base class (RenderFrameBase) was removed a few months ago because it turned
out to have only code that wasn't relevant to Blink. But I've implemented your
suggestion.

+        m_graphicsLayer->setContentsToPlatformLayer(toHTMLFrameOwnerElement(renderer->node())->contentFrame()->platformLayer());

[eseidel, 2013/12/11 18:50:01]

You just if-checked this long lookup, maybe you wanted to save it in a local?

[kenrb, 2013/12/11 22:44:56]

Done.

     } else if (renderer->isVideo()) {
         HTMLMediaElement* mediaElement = toHTMLMediaElement(renderer->node());
         m_graphicsLayer->setContentsToPlatformLayer(mediaElement->platformLayer());