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

services/ui/public/cpp/output_surface.h

Index: services/ui/public/cpp/output_surface.h
diff --git a/services/ui/public/cpp/output_surface.h b/services/ui/public/cpp/output_surface.h
index 1d3c560410b0c87c281cf1be88121336c0d2f018..399c922f9e2ab0866e71bea29392d7928ac158d5 100644
--- a/services/ui/public/cpp/output_surface.h
+++ b/services/ui/public/cpp/output_surface.h
@@ -12,13 +12,15 @@
 #include "services/ui/public/cpp/window_surface.h"
 #include "services/ui/public/cpp/window_surface_client.h"
 
-namespace ui {
+namespace gpu {
+class GpuChannelHost;
+}
 
-class GpuService;
+namespace ui {
 
 class OutputSurface : public cc::OutputSurface, public WindowSurfaceClient {
  public:
-  OutputSurface(GpuService* gpu_service,
+  OutputSurface(scoped_refptr<gpu::GpuChannelHost> gpu_channel_host,
                 std::unique_ptr<WindowSurface> surface);
   ~OutputSurface() override;