Avoid destroying surface before the parent surface stops referencing it.

mojo/aura/surface_context_factory.cc

Index: mojo/aura/surface_context_factory.cc
diff --git a/mojo/aura/surface_context_factory.cc b/mojo/aura/surface_context_factory.cc
index 1e560296731af6f7b9e861cc2fdaef4761446484..9f1e77a1735ad46d1835d472adcff9227a6507b5 100644
--- a/mojo/aura/surface_context_factory.cc
+++ b/mojo/aura/surface_context_factory.cc
@@ -6,6 +6,7 @@
 
 #include "cc/output/output_surface.h"
 #include "cc/resources/shared_bitmap_manager.h"
+#include "cc/surfaces/surface_id_allocator.h"
 #include "mojo/public/interfaces/application/shell.mojom.h"
 #include "mojo/services/public/cpp/view_manager/view.h"
 #include "ui/compositor/reflector.h"
@@ -55,4 +56,9 @@ base::MessageLoopProxy* SurfaceContextFactory::GetCompositorMessageLoop() {
   return nullptr;
 }
 
+scoped_ptr<cc::SurfaceIdAllocator>
+SurfaceContextFactory::CreateSurfaceIdAllocator() {
+  return nullptr;
+}
+
 }  // namespace mojo