ui::ContextFactory should not create SurfaceIdAllocators

ui/compositor/test/in_process_context_factory.cc

Index: ui/compositor/test/in_process_context_factory.cc
diff --git a/ui/compositor/test/in_process_context_factory.cc b/ui/compositor/test/in_process_context_factory.cc
index 30d73b1bcaeb5170ea4e69fc2528175e8f75f478..6e9b9618280d83a65f3feb25c87b83a385ccf9a6 100644
--- a/ui/compositor/test/in_process_context_factory.cc
+++ b/ui/compositor/test/in_process_context_factory.cc
@@ -247,13 +247,8 @@ cc::TaskGraphRunner* InProcessContextFactory::GetTaskGraphRunner() {
   return &task_graph_runner_;
 }
 
-std::unique_ptr<cc::SurfaceIdAllocator>
-InProcessContextFactory::CreateSurfaceIdAllocator() {
-  std::unique_ptr<cc::SurfaceIdAllocator> allocator(
-      new cc::SurfaceIdAllocator(next_surface_client_id_++));
-  if (surface_manager_)
-    allocator->RegisterSurfaceClientId(surface_manager_);
-  return allocator;
+uint32_t InProcessContextFactory::AllocateSurfaceClientId() {
+  return next_surface_client_id_++;
 }
 
 cc::SurfaceManager* InProcessContextFactory::GetSurfaceManager() {