Avoid destroying surface before the parent surface stops referencing it.

mojo/aura/context_factory_mojo.cc

Index: mojo/aura/context_factory_mojo.cc
diff --git a/mojo/aura/context_factory_mojo.cc b/mojo/aura/context_factory_mojo.cc
index 6b2b709cdcd75a7aa9c3c7c0020a6aaaef7e5a04..38355ce5d78f0dd2130b7713591fbbb85cd55ff2 100644
--- a/mojo/aura/context_factory_mojo.cc
+++ b/mojo/aura/context_factory_mojo.cc
@@ -8,6 +8,7 @@
 #include "cc/output/output_surface.h"
 #include "cc/output/software_output_device.h"
 #include "cc/resources/shared_bitmap_manager.h"
+#include "cc/surfaces/surface_id_allocator.h"
 #include "mojo/aura/window_tree_host_mojo.h"
 #include "skia/ext/platform_canvas.h"
 #include "ui/compositor/reflector.h"
@@ -93,7 +94,8 @@ class TestSharedBitmapManager : public cc::SharedBitmapManager {
 }  // namespace
 
 ContextFactoryMojo::ContextFactoryMojo()
-    : shared_bitmap_manager_(new TestSharedBitmapManager()) {
+    : shared_bitmap_manager_(new TestSharedBitmapManager()),
+      next_surface_id_namespace_(1u) {
 }
 
 ContextFactoryMojo::~ContextFactoryMojo() {}
@@ -133,4 +135,10 @@ base::MessageLoopProxy* ContextFactoryMojo::GetCompositorMessageLoop() {
   return NULL;
 }
 
+scoped_ptr<cc::SurfaceIdAllocator>
+ContextFactoryMojo::CreateSurfaceIdAllocator() {
+  return make_scoped_ptr(
+      new cc::SurfaceIdAllocator(next_surface_id_namespace_++));
+}
+
 }  // namespace mojo