Add a new ozone switch to enable surfaceless output mode.

ui/ozone/public/surface_factory_ozone.cc

Index: ui/ozone/public/surface_factory_ozone.cc
diff --git a/ui/ozone/public/surface_factory_ozone.cc b/ui/ozone/public/surface_factory_ozone.cc
index dac23f53be17dfbe2d6e099f6a3cb49e1fafb4fd..ba50db8ed89fafe72e340f2eaa3b52d4543eb662 100644
--- a/ui/ozone/public/surface_factory_ozone.cc
+++ b/ui/ozone/public/surface_factory_ozone.cc
@@ -41,6 +41,12 @@ scoped_ptr<SurfaceOzoneEGL> SurfaceFactoryOzone::CreateEGLSurfaceForWidget(
   return scoped_ptr<SurfaceOzoneEGL>();
 }
 
+scoped_ptr<SurfaceOzoneEGL> SurfaceFactoryOzone::CreateEmptyEGLSurfaceForWidget(
+    gfx::AcceleratedWidget widget) {
+  NOTIMPLEMENTED();
+  return scoped_ptr<SurfaceOzoneCanvas>();
+}
+
 scoped_ptr<SurfaceOzoneCanvas> SurfaceFactoryOzone::CreateCanvasForWidget(
     gfx::AcceleratedWidget widget) {
   NOTIMPLEMENTED();