WIP: move OffscreenCanvas into new display compositor

services/ui/surfaces/display_compositor.cc

Index: services/ui/surfaces/display_compositor.cc
diff --git a/services/ui/surfaces/display_compositor.cc b/services/ui/surfaces/display_compositor.cc
index b022b427513302d476642d788cae236145c217c2..2da6ae9f30e1ffca0b60af92bbc233ff0ad4ea42 100644
--- a/services/ui/surfaces/display_compositor.cc
+++ b/services/ui/surfaces/display_compositor.cc
@@ -17,6 +17,7 @@
 #include "cc/surfaces/surface.h"
 #include "components/display_compositor/gpu_display_compositor_frame_sink.h"
 #include "components/display_compositor/gpu_offscreen_compositor_frame_sink.h"
+#include "components/display_compositor/offscreen_canvas_compositor_frame_sink.h"
 #include "gpu/command_buffer/client/shared_memory_limits.h"
 #include "gpu/ipc/gpu_in_process_thread_service.h"
 #include "mojo/public/cpp/bindings/strong_binding.h"
@@ -44,10 +45,19 @@ DisplayCompositor::DisplayCompositor(
       binding_(this, std::move(request)) {
   manager_.AddObserver(this);
 }
+DisplayCompositor::DisplayCompositor(
+    cc::mojom::DisplayCompositorRequest request,
+    cc::SurfaceManager* surfacemanager)
+    : manager_of_system_(surfacemanager), binding_(this, std::move(request)) {
+  if (manager_of_system_)
+    manager_of_system_->AddObserver(this);
+}
 
 DisplayCompositor::~DisplayCompositor() {
   DCHECK(thread_checker_.CalledOnValidThread());
   manager_.RemoveObserver(this);
+  if (manager_of_system_)
+    manager_of_system_->RemoveObserver(this);
 }
 
 void DisplayCompositor::OnClientConnectionLost(
@@ -108,6 +118,19 @@ void DisplayCompositor::CreateOffscreenCompositorFrameSink(
           std::move(private_request), std::move(client));
 }
 
+void DisplayCompositor::CreateOffscreenCanvasCompositorFrameSink(
+    const cc::FrameSinkId& frame_sink_id,
+    cc::mojom::MojoCompositorFrameSinkRequest request,
+    cc::mojom::MojoCompositorFrameSinkClientPtr client) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK_EQ(0u, compositor_frame_sinks_.count(frame_sink_id));
+
+  compositor_frame_sinks_[frame_sink_id] =
+      base::MakeUnique<display_compositor::OffscreenCanvasCompositorFrameSink>(
+          this, manager_of_system_, frame_sink_id, std::move(request),
+          std::move(client));
+}
+
 std::unique_ptr<cc::Display> DisplayCompositor::CreateDisplay(
     const cc::FrameSinkId& frame_sink_id,
     gpu::SurfaceHandle surface_handle,