Allow out-of-process iframes to render to compositing surfaces.

content/renderer/render_frame_proxy.cc

Index: content/renderer/render_frame_proxy.cc
diff --git a/content/renderer/render_frame_proxy.cc b/content/renderer/render_frame_proxy.cc
index 4dc9bbf220d2310d9511923486ccdfe8e0f65955..29e7a0301336c71c818dd44e352a7145d58f9718 100644
--- a/content/renderer/render_frame_proxy.cc
+++ b/content/renderer/render_frame_proxy.cc
@@ -210,6 +210,7 @@ bool RenderFrameProxy::OnMessageReceived(const IPC::Message& msg) {
     IPC_MESSAGE_HANDLER(FrameMsg_ChildFrameProcessGone, OnChildFrameProcessGone)
     IPC_MESSAGE_HANDLER_GENERIC(FrameMsg_CompositorFrameSwapped,
                                 OnCompositorFrameSwapped(msg))
+    IPC_MESSAGE_HANDLER(FrameMsg_SetChildFrameSurface, OnSetChildFrameSurface)
     IPC_MESSAGE_HANDLER(FrameMsg_DisownOpener, OnDisownOpener)
     IPC_MESSAGE_HANDLER(FrameMsg_DidStartLoading, OnDidStartLoading)
     IPC_MESSAGE_HANDLER(FrameMsg_DidStopLoading, OnDidStopLoading)
@@ -266,6 +267,27 @@ void RenderFrameProxy::OnCompositorFrameSwapped(const IPC::Message& message) {
       get<0>(param).shared_memory_handle);
 }
 
+void RenderFrameProxy::OnSetChildFrameSurface(
+    const cc::SurfaceId& surface_id,
+    const gfx::Size& frame_size,
+    float scale_factor,
+    const cc::SurfaceSequence& sequence) {
+  // If this WebFrame has already been detached, its parent will be null. This
+  // can happen when swapping a WebRemoteFrame with a WebLocalFrame, where this
+  // message may arrive after the frame was removed from the frame tree, but
+  // before the frame has been destroyed. http://crbug.com/446575.
+  if (!web_frame()->parent())
+    return;
+
+  if (!compositing_helper_.get()) {
+    compositing_helper_ =
+        ChildFrameCompositingHelper::CreateForRenderFrameProxy(this);
+    compositing_helper_->EnableCompositing(true);
+  }
+  compositing_helper_->OnSetSurface(surface_id, frame_size, scale_factor,
+                                    sequence);
+}
+
 void RenderFrameProxy::OnDisownOpener() {
   // TODO(creis): We should only see this for main frames for now.  To support
   // disowning the opener on subframes, we will need to move WebContentsImpl's