Standardize usage of virtual/override/final in sync/

sync/test/engine/mock_model_type_sync_worker.h

Index: sync/test/engine/mock_model_type_sync_worker.h
diff --git a/sync/test/engine/mock_model_type_sync_worker.h b/sync/test/engine/mock_model_type_sync_worker.h
index 2078c8476875dba4d788bace6c5c02fb239a906d..688cfc3612e5502b81fe88ba19cae8728fdb1bfe 100644
--- a/sync/test/engine/mock_model_type_sync_worker.h
+++ b/sync/test/engine/mock_model_type_sync_worker.h
@@ -21,10 +21,10 @@ namespace syncer {
 class MockModelTypeSyncWorker : public ModelTypeSyncWorker {
  public:
   MockModelTypeSyncWorker();
-  virtual ~MockModelTypeSyncWorker();
+  ~MockModelTypeSyncWorker() override;
 
   // Implementation of ModelTypeSyncWorker.
-  virtual void EnqueueForCommit(const CommitRequestDataList& list) override;
+  void EnqueueForCommit(const CommitRequestDataList& list) override;
 
   // Getters to inspect the requests sent to this object.
   size_t GetNumCommitRequestLists() const;