Aura-Mus: Avoid creating StubSurfaceReferenceFactory's on every surface ID change

BUG=none

Review-Url: https://codereview.chromium.org/2848273002
Cr-Commit-Position: refs/heads/master@{#468411}

ui/aura/mus/client_surface_embedder.cc

@@ -46,14 +46,14 @@ ClientSurfaceEmbedder::ClientSurfaceEmbedder(
   // this is the case with window decorations provided by Window Manager.
   // This content should appear underneath the content of the embedded client.
   window_->layer()->StackAtTop(surface_layer_.get());
+  ref_factory_ = new StubSurfaceReferenceFactory();
 }
 
 ClientSurfaceEmbedder::~ClientSurfaceEmbedder() = default;
 
 void ClientSurfaceEmbedder::SetPrimarySurfaceInfo(
     const cc::SurfaceInfo& surface_info) {
-  surface_layer_->SetShowPrimarySurface(
-      surface_info, make_scoped_refptr(new StubSurfaceReferenceFactory));
+  surface_layer_->SetShowPrimarySurface(surface_info, ref_factory_);
   surface_layer_->SetBounds(gfx::Rect(window_->bounds().size()));
 }
 

ui/aura/mus/client_surface_embedder.h

@@ -5,6 +5,8 @@
 #include <memory>
 
 #include "base/macros.h"
+#include "base/memory/ref_counted.h"
+#include "cc/surfaces/surface_reference_factory.h"
 #include "ui/gfx/geometry/insets.h"
 
 namespace cc {
@@ -62,6 +64,8 @@ class ClientSurfaceEmbedder {
 
   gfx::Insets client_area_insets_;
 
+  scoped_refptr<cc::SurfaceReferenceFactory> ref_factory_;
+
   DISALLOW_COPY_AND_ASSIGN(ClientSurfaceEmbedder);
 };