Standardize usage of virtual/override/final in sync/

sync/test/null_directory_change_delegate.h

Index: sync/test/null_directory_change_delegate.h
diff --git a/sync/test/null_directory_change_delegate.h b/sync/test/null_directory_change_delegate.h
index c55b27e1c905100d09f4ad61e762b8438d339d12..a37e6708ce76fb7604dc8c6b1674d6946b6074d5 100644
--- a/sync/test/null_directory_change_delegate.h
+++ b/sync/test/null_directory_change_delegate.h
@@ -14,20 +14,20 @@ namespace syncable {
 // DirectoryChangeDelegate that does nothing in all delegate methods.
 class NullDirectoryChangeDelegate : public DirectoryChangeDelegate {
  public:
-  virtual ~NullDirectoryChangeDelegate();
+  ~NullDirectoryChangeDelegate() override;
 
-  virtual void HandleCalculateChangesChangeEventFromSyncApi(
+  void HandleCalculateChangesChangeEventFromSyncApi(
       const ImmutableWriteTransactionInfo& write_transaction_info,
       BaseTransaction* trans,
       std::vector<int64>* entries_changed) override;
-  virtual void HandleCalculateChangesChangeEventFromSyncer(
+  void HandleCalculateChangesChangeEventFromSyncer(
       const ImmutableWriteTransactionInfo& write_transaction_info,
       BaseTransaction* trans,
       std::vector<int64>* entries_changed) override;
-  virtual ModelTypeSet HandleTransactionEndingChangeEvent(
+  ModelTypeSet HandleTransactionEndingChangeEvent(
       const ImmutableWriteTransactionInfo& write_transaction_info,
       BaseTransaction* trans) override;
-  virtual void HandleTransactionCompleteChangeEvent(
+  void HandleTransactionCompleteChangeEvent(
       ModelTypeSet models_with_changes) override;
 };