services/ui: Use a gpu::GpuChannelHost when creating ui::OutputSurface.

ui/views/mus/surface_context_factory.cc

Index: ui/views/mus/surface_context_factory.cc
diff --git a/ui/views/mus/surface_context_factory.cc b/ui/views/mus/surface_context_factory.cc
index 6d22e456e37121cf76a27e3a47d8819687643266..36aef012734e28da2243d549ffd9f397cf51d8b9 100644
--- a/ui/views/mus/surface_context_factory.cc
+++ b/ui/views/mus/surface_context_factory.cc
@@ -39,8 +39,9 @@ void SurfaceContextFactory::CreateOutputSurface(
   ui::Window* window = compositor->window();
   NativeWidgetMus* native_widget = NativeWidgetMus::GetForWindow(window);
   ui::mojom::SurfaceType surface_type = native_widget->surface_type();
-  std::unique_ptr<cc::OutputSurface> surface(new ui::OutputSurface(
-      gpu_service_, window->RequestSurface(surface_type)));
+  std::unique_ptr<cc::OutputSurface> surface(
+      new ui::OutputSurface(gpu_service_->EstablishGpuChannelSync(),
+                            window->RequestSurface(surface_type)));
   compositor->SetOutputSurface(std::move(surface));
 }