Add a new ozone switch to enable surfaceless output mode.

ui/ozone/platform/dri/gbm_surface_factory.cc

Index: ui/ozone/platform/dri/gbm_surface_factory.cc
diff --git a/ui/ozone/platform/dri/gbm_surface_factory.cc b/ui/ozone/platform/dri/gbm_surface_factory.cc
index 1920cc662c68a8d90687f510b092567e9b6f8237..bab30ff11a6de6db523ab1cf11d22ca575d7f366 100644
--- a/ui/ozone/platform/dri/gbm_surface_factory.cc
+++ b/ui/ozone/platform/dri/gbm_surface_factory.cc
@@ -97,19 +97,22 @@ scoped_ptr<SurfaceOzoneEGL> GbmSurfaceFactory::CreateEGLSurfaceForWidget(
   DCHECK(state_ == INITIALIZED);
   ResetCursor(widget);
 
-  if (allow_surfaceless_) {
-    return scoped_ptr<SurfaceOzoneEGL>(
-        new GbmSurfaceless(screen_manager_->GetDisplayController(widget)));
-  } else {
-    scoped_ptr<GbmSurface> surface(
-        new GbmSurface(screen_manager_->GetDisplayController(widget),
-                       device_,
-                       drm_));
-    if (!surface->Initialize())
-      return scoped_ptr<SurfaceOzoneEGL>();
-
-    return surface.PassAs<SurfaceOzoneEGL>();
-  }
+  scoped_ptr<GbmSurface> surface(
+      new GbmSurface(screen_manager_->GetDisplayController(widget),
+                     device_,
+                     drm_));
+  if (!surface->Initialize())
+    return scoped_ptr<SurfaceOzoneEGL>();
+
+  return surface.PassAs<SurfaceOzoneEGL>();
+}
+
+scoped_ptr<SurfaceOzoneEGL> GbmSurfaceFactory::CreateEmptyEGLSurfaceForWidget(
+    gfx::AcceleratedWidget widget) {
+  if (!allow_surfaceless_)
+    return scoped_ptr<SurfaceOzoneEGL>();
+  return scoped_ptr<SurfaceOzoneEGL>(
+      new GbmSurfaceless(screen_manager_->GetDisplayController(widget)));
 }
 
 scoped_refptr<ui::NativePixmap> GbmSurfaceFactory::CreateNativePixmap(