Implement temporary reference assignment with DisplayCompositor.

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 fb14a1ee4389f6008f89401827d1d844a43ee904..94d57c74d34bde4ad83a7598c792a1b9c7c4d3c0 100644
--- a/services/ui/surfaces/display_compositor.cc
+++ b/services/ui/surfaces/display_compositor.cc
@@ -108,6 +108,11 @@ void DisplayCompositor::CreateCompositorFrameSink(
           std::move(private_request), std::move(client));
 }
 
+void DisplayCompositor::DropTemporaryReference(
+    const cc::SurfaceId& surface_id) {
+  manager_.DropTemporaryReference(surface_id);
+}
+
 std::unique_ptr<cc::Display> DisplayCompositor::CreateDisplay(
     const cc::FrameSinkId& frame_sink_id,
     gpu::SurfaceHandle surface_handle,
@@ -163,6 +168,10 @@ void DisplayCompositor::OnSurfaceCreated(const cc::SurfaceInfo& surface_info) {
   DCHECK(thread_checker_.CalledOnValidThread());
   DCHECK_GT(surface_info.device_scale_factor(), 0.0f);
 
+  // TODO(kylechar): |client_| will try to find an owner for the temporary
+  // reference to the new surface. With surface synchronization this might not

[Fady Samuel, 2017/02/24 18:07:38]

More details please? Why won't this be necessary, again? Is it because a parent
may have already claimed ownership?

[kylechar, 2017/02/28 18:07:15]

Done.

+  // be necessary in all cases, so we should let |client_| know if there is a
+  // temporary reference or not.
   if (client_)
     client_->OnSurfaceCreated(surface_info);
 }