components: Add out-of-line copy ctors for complex classes.

components/sync_driver/data_type_manager.cc

Index: components/sync_driver/data_type_manager.cc
diff --git a/components/sync_driver/data_type_manager.cc b/components/sync_driver/data_type_manager.cc
index 99dc70ae5edd64c2e0ff7ca114ec918e26168725..1288b2379382d0f684b3e6c7804405a4b91ad38f 100644
--- a/components/sync_driver/data_type_manager.cc
+++ b/components/sync_driver/data_type_manager.cc
@@ -16,6 +16,9 @@ DataTypeManager::ConfigureResult::ConfigureResult(
     : status(status), requested_types(requested_types) {
 }
 
+DataTypeManager::ConfigureResult::ConfigureResult(
+    const ConfigureResult& other) = default;
+
 DataTypeManager::ConfigureResult::~ConfigureResult() {
 }