[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 e40e6739ad0ec040512e75df3e0d6fcb829f72cd..8b35a10e50204c6c5c916652a68e742b8a24df1e 100644
--- a/components/sync/engine/fake_sync_engine.cc
+++ b/components/sync/engine/fake_sync_engine.cc
@@ -24,6 +24,8 @@ void FakeSyncEngine::TriggerRefresh(const ModelTypeSet& types) {}
 
 void FakeSyncEngine::UpdateCredentials(const SyncCredentials& credentials) {}
 
+void FakeSyncEngine::StartConfiguration() {}
+
 void FakeSyncEngine::StartSyncingWithServer() {}
 
 void FakeSyncEngine::SetEncryptionPassphrase(const std::string& passphrase,
@@ -39,6 +41,11 @@ 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() {}
 
 void FakeSyncEngine::ActivateDirectoryDataType(