Centralize FrameSinkId allocation in one place

ui/compositor/test/in_process_context_factory.h

Index: ui/compositor/test/in_process_context_factory.h
diff --git a/ui/compositor/test/in_process_context_factory.h b/ui/compositor/test/in_process_context_factory.h
index 72924b66e63df6084f63884206662727338ad9af..9d40c12143c34b409d14d4844bac20e369c0d1cc 100644
--- a/ui/compositor/test/in_process_context_factory.h
+++ b/ui/compositor/test/in_process_context_factory.h
@@ -10,6 +10,7 @@
 
 #include "base/macros.h"
 #include "cc/surfaces/display.h"
+#include "cc/surfaces/frame_sink_id_allocator.h"
 #include "cc/test/test_gpu_memory_buffer_manager.h"
 #include "cc/test/test_image_factory.h"
 #include "cc/test/test_shared_bitmap_manager.h"
@@ -84,7 +85,7 @@ class InProcessContextFactory : public ContextFactory,
   cc::TestGpuMemoryBufferManager gpu_memory_buffer_manager_;
   cc::TestImageFactory image_factory_;
   cc::TestTaskGraphRunner task_graph_runner_;
-  uint32_t next_surface_sink_id_;
+  cc::FrameSinkIdAllocator frame_sink_id_allocator_;
   bool use_test_surface_;
   bool context_factory_for_test_;
   cc::SurfaceManager* surface_manager_;