[Sync] Move DataTypeErrorHandler to //sync.

sync/BUILD.gn

Index: sync/BUILD.gn
diff --git a/sync/BUILD.gn b/sync/BUILD.gn
index a859663a90d6450750e8df6783b12c714c97b803..7bdfa6675856870f5845d84f729a602f45a88706 100644
--- a/sync/BUILD.gn
+++ b/sync/BUILD.gn
@@ -225,6 +225,7 @@ source_set("sync_core") {
     "internal_api/public/data_type_association_stats.h",
     "internal_api/public/data_type_debug_info_listener.cc",
     "internal_api/public/data_type_debug_info_listener.h",
+    "internal_api/public/data_type_error_handler.h",
     "internal_api/public/delete_journal.h",
     "internal_api/public/engine/model_safe_worker.cc",
     "internal_api/public/engine/model_safe_worker.h",
@@ -546,6 +547,7 @@ static_library("test_support_sync_core") {
 static_library("test_support_sync_internal_api") {
   testonly = true
   sources = [
+    "internal_api/public/test/data_type_error_handler_mock.h",
     "internal_api/public/test/fake_model_type_connector.h",
     "internal_api/public/test/fake_model_type_processor.h",
     "internal_api/public/test/fake_sync_manager.h",
@@ -554,6 +556,7 @@ static_library("test_support_sync_internal_api") {
     "internal_api/public/test/test_entry_factory.h",
     "internal_api/public/test/test_internal_components_factory.h",
     "internal_api/public/test/test_user_share.h",
+    "internal_api/test/data_type_error_handler_mock.cc",
     "internal_api/test/fake_model_type_connector.cc",
     "internal_api/test/fake_model_type_processor.cc",
     "internal_api/test/fake_sync_manager.cc",