WIP: move OffscreenCanvas into new display compositor

services/ui/surfaces/display_compositor.h

Index: services/ui/surfaces/display_compositor.h
diff --git a/services/ui/surfaces/display_compositor.h b/services/ui/surfaces/display_compositor.h
index 286b1a757b0bdc0d2a813d6c18dc8e17a9dcf02b..56a27f3bcf804b9d3e67c298e20090b13a0b2048 100644
--- a/services/ui/surfaces/display_compositor.h
+++ b/services/ui/surfaces/display_compositor.h
@@ -58,6 +58,8 @@ class DisplayCompositor
       gpu::ImageFactory* image_factory,
       cc::mojom::DisplayCompositorRequest request,
       cc::mojom::DisplayCompositorClientPtr client);
+  DisplayCompositor(cc::mojom::DisplayCompositorRequest request,
+                    cc::SurfaceManager* surfacemanager);
   ~DisplayCompositor() override;
 
   cc::SurfaceManager* manager() { return &manager_; }
@@ -83,6 +85,11 @@ class DisplayCompositor
       cc::mojom::MojoCompositorFrameSinkPrivateRequest private_request,
       cc::mojom::MojoCompositorFrameSinkClientPtr client) override;
 
+  void CreateOffscreenCanvasCompositorFrameSink(
+      const cc::FrameSinkId& frame_sink_id,
+      cc::mojom::MojoCompositorFrameSinkRequest request,
+      cc::mojom::MojoCompositorFrameSinkClientPtr client) override;
+
  private:
   std::unique_ptr<cc::Display> CreateDisplay(
       const cc::FrameSinkId& frame_sink_id,
@@ -115,6 +122,8 @@ class DisplayCompositor
   // destroyed in order to ensure that all other objects that depend on it have
   // access to a valid pointer for the entirety of their liftimes.
   cc::SurfaceManager manager_;
+  // TODO(xing.xu): when new display compositor is done, remove this.
+  cc::SurfaceManager* manager_of_system_;
 
   scoped_refptr<gpu::InProcessCommandBuffer::Service> gpu_service_;
   std::unique_ptr<gpu::GpuMemoryBufferManager> gpu_memory_buffer_manager_;