Mustash: Ensure surfaces submitted to Mus by WM and embedders contain Surfaces with embeded content.

ui/aura/mus/window_port_mus.cc

Index: ui/aura/mus/window_port_mus.cc
diff --git a/ui/aura/mus/window_port_mus.cc b/ui/aura/mus/window_port_mus.cc
index 8f7aa82d3847ae808b091b13292475694ff6680e..e8eb176d658945687588df3b2758f123cb437f46 100644
--- a/ui/aura/mus/window_port_mus.cc
+++ b/ui/aura/mus/window_port_mus.cc
@@ -6,6 +6,7 @@
 
 #include "ui/aura/client/aura_constants.h"
 #include "ui/aura/client/transient_window_client.h"
+#include "ui/aura/mus/client_surface_embedder.h"
 #include "ui/aura/mus/property_converter.h"
 #include "ui/aura/mus/surface_id_handler.h"
 #include "ui/aura/mus/window_tree_client.h"
@@ -255,10 +256,22 @@ void WindowPortMus::SetSurfaceIdFromServer(
     }
   }
   WindowPortMus* parent = Get(window_->parent());
+  // TODO(mfomitchev): This is unused. We probably don't need this.
   if (parent && parent->surface_id_handler_) {
     parent->surface_id_handler_->OnChildWindowSurfaceChanged(window_,
                                                              &surface_info);
   }
+
+  // The fact that SetSurfaceIdFromServer was called means that this window
+  // corresponds to an embedded client.
+  if (!client_surface_embedder && surface_info)
+    client_surface_embedder = base::MakeUnique<ClientSurfaceEmbedder>(window_);
+
+  if (surface_info)
+    client_surface_embedder->UpdateSurface(*surface_info.get());
+  else
+    client_surface_embedder.reset();
+
   surface_info_ = std::move(surface_info);
 }