Update Context Client Visibility to use Scoped Pattern

cc/trees/layer_tree_host_impl.h

Index: cc/trees/layer_tree_host_impl.h
diff --git a/cc/trees/layer_tree_host_impl.h b/cc/trees/layer_tree_host_impl.h
index 31a899ea7a9b6d2a5c5f39c32220345f3ca564d6..95bb964d029b1f43fe08f12278646d4cf44755d4 100644
--- a/cc/trees/layer_tree_host_impl.h
+++ b/cc/trees/layer_tree_host_impl.h
@@ -42,6 +42,7 @@
 #include "cc/trees/layer_tree_settings.h"
 #include "cc/trees/mutator_host_client.h"
 #include "cc/trees/task_runner_provider.h"
+#include "gpu/command_buffer/client/context_support.h"
 #include "ui/gfx/geometry/rect.h"
 
 namespace gfx {
@@ -721,6 +722,11 @@ class CC_EXPORT LayerTreeHostImpl
 
   OutputSurface* output_surface_;
 
+  std::unique_ptr<gpu::ContextSupport::ScopedVisibility>
+      main_context_client_visibility_;
+  std::unique_ptr<gpu::ContextSupport::ScopedVisibility>
+      worker_context_client_visibility_;
+
   std::unique_ptr<ResourceProvider> resource_provider_;
   bool need_update_gpu_rasterization_status_;
   bool content_is_suitable_for_gpu_rasterization_;