Standardize usage of virtual/override/final in sync/

sync/test/engine/mock_update_handler.h

Index: sync/test/engine/mock_update_handler.h
diff --git a/sync/test/engine/mock_update_handler.h b/sync/test/engine/mock_update_handler.h
index 74393dfbf666299eaf77de5c5465dd5665875582..6993ab2ce1bacf0797babff67bbb0a97a28e50cd 100644
--- a/sync/test/engine/mock_update_handler.h
+++ b/sync/test/engine/mock_update_handler.h
@@ -15,20 +15,19 @@ namespace syncer {
 class MockUpdateHandler : public UpdateHandler {
  public:
   explicit MockUpdateHandler(ModelType type);
-  virtual ~MockUpdateHandler();
+  ~MockUpdateHandler() override;
 
   // UpdateHandler implementation.
-  virtual void GetDownloadProgress(
+  void GetDownloadProgress(
       sync_pb::DataTypeProgressMarker* progress_marker) const override;
-  virtual void GetDataTypeContext(sync_pb::DataTypeContext* context) const
-      override;
-  virtual SyncerError ProcessGetUpdatesResponse(
+  void GetDataTypeContext(sync_pb::DataTypeContext* context) const override;
+  SyncerError ProcessGetUpdatesResponse(
       const sync_pb::DataTypeProgressMarker& progress_marker,
       const sync_pb::DataTypeContext& mutated_context,
       const SyncEntityList& applicable_updates,
       sessions::StatusController* status) override;
-  virtual void ApplyUpdates(sessions::StatusController* status) override;
-  virtual void PassiveApplyUpdates(sessions::StatusController* status) override;
+  void ApplyUpdates(sessions::StatusController* status) override;
+  void PassiveApplyUpdates(sessions::StatusController* status) override;
 
   // Returns the number of times ApplyUpdates() was invoked.
   int GetApplyUpdatesCount();