[Sync] Improve MetadataChangeList usage for types using ModelTypeStore.

components/sync/BUILD.gn

Index: components/sync/BUILD.gn
diff --git a/components/sync/BUILD.gn b/components/sync/BUILD.gn
index 671726d3076c63ae2964dcd4f6545c7257ee17d5..793fbe4e371f616e6dd99c8b1a8117769fec2523 100644
--- a/components/sync/BUILD.gn
+++ b/components/sync/BUILD.gn
@@ -428,8 +428,6 @@ static_library("sync") {
     "model/model_type_sync_bridge.h",
     "model/mutable_data_batch.cc",
     "model/mutable_data_batch.h",
-    "model/simple_metadata_change_list.cc",
-    "model/simple_metadata_change_list.h",
     "model/string_ordinal.h",
     "model/sync_change.cc",
     "model/sync_change.h",
@@ -446,9 +444,13 @@ static_library("sync") {
     "model/syncable_service.cc",
     "model/syncable_service.h",
     "model/time.h",
+    "model_impl/accumulating_metadata_change_list.cc",
+    "model_impl/accumulating_metadata_change_list.h",
     "model_impl/attachments/attachment_service_impl.cc",
     "model_impl/attachments/attachment_service_impl.h",
     "model_impl/attachments/task_queue.h",
+    "model_impl/in_memory_metadata_change_list.cc",
+    "model_impl/in_memory_metadata_change_list.h",
     "model_impl/model_type_store_backend.cc",
     "model_impl/model_type_store_backend.h",
     "model_impl/model_type_store_impl.cc",
@@ -901,11 +903,11 @@ source_set("unit_tests") {
     "model/entity_data_unittest.cc",
     "model/model_type_sync_bridge_unittest.cc",
     "model/mutable_data_batch_unittest.cc",
-    "model/simple_metadata_change_list_unittest.cc",
     "model/sync_change_unittest.cc",
     "model/sync_data_unittest.cc",
     "model/sync_error_unittest.cc",
     "model/sync_merge_result_unittest.cc",
+    "model_impl/accumulating_metadata_change_list_unittest.cc",
     "model_impl/attachments/attachment_service_impl_unittest.cc",
     "model_impl/attachments/task_queue_unittest.cc",
     "model_impl/model_type_store_backend_unittest.cc",