Revert of [Sync] Make directory types registration explicit in ModelTypeRegistry

components/sync/engine/fake_sync_engine.cc

Index: components/sync/engine/fake_sync_engine.cc
diff --git a/components/sync/engine/fake_sync_engine.cc b/components/sync/engine/fake_sync_engine.cc
index 8b35a10e50204c6c5c916652a68e742b8a24df1e..e40e6739ad0ec040512e75df3e0d6fcb829f72cd 100644
--- a/components/sync/engine/fake_sync_engine.cc
+++ b/components/sync/engine/fake_sync_engine.cc
@@ -24,8 +24,6 @@
 
 void FakeSyncEngine::UpdateCredentials(const SyncCredentials& credentials) {}
 
-void FakeSyncEngine::StartConfiguration() {}
-
 void FakeSyncEngine::StartSyncingWithServer() {}
 
 void FakeSyncEngine::SetEncryptionPassphrase(const std::string& passphrase,
@@ -40,11 +38,6 @@
 void FakeSyncEngine::Shutdown(ShutdownReason reason) {}
 
 void FakeSyncEngine::ConfigureDataTypes(ConfigureParams params) {}
-
-void FakeSyncEngine::RegisterDirectoryDataType(ModelType type,
-                                               ModelSafeGroup group) {}
-
-void FakeSyncEngine::UnregisterDirectoryDataType(ModelType type) {}
 
 void FakeSyncEngine::EnableEncryptEverything() {}