Mojo C++ bindings: remove some usage of AssociatedGroup from user code.

services/ui/ws/frame_generator.cc

Index: services/ui/ws/frame_generator.cc
diff --git a/services/ui/ws/frame_generator.cc b/services/ui/ws/frame_generator.cc
index ea2286397c32f5c3dc7a52b82a739a9041399bfd..9937aec915f377a018a5ff1f714ab01db0ae1ab4 100644
--- a/services/ui/ws/frame_generator.cc
+++ b/services/ui/ws/frame_generator.cc
@@ -45,12 +45,10 @@ FrameGenerator::~FrameGenerator() {
 void FrameGenerator::OnAcceleratedWidgetAvailable(
     gfx::AcceleratedWidget widget) {
   DCHECK_NE(gfx::kNullAcceleratedWidget, widget);
-  auto associated_group =
-      root_window_->delegate()->GetDisplayCompositorAssociatedGroup();
   cc::mojom::MojoCompositorFrameSinkAssociatedRequest sink_request =
-      mojo::MakeRequest(&compositor_frame_sink_, associated_group);
+      mojo::MakeRequest(&compositor_frame_sink_);
   cc::mojom::DisplayPrivateAssociatedRequest display_request =
-      mojo::MakeRequest(&display_private_, associated_group);
+      mojo::MakeRequest(&display_private_);
   root_window_->CreateDisplayCompositorFrameSink(
       widget, std::move(sink_request), binding_.CreateInterfacePtrAndBind(),
       std::move(display_request));