Standardize usage of virtual/override/final in sync/

sync/test/engine/fake_model_worker.h

Index: sync/test/engine/fake_model_worker.h
diff --git a/sync/test/engine/fake_model_worker.h b/sync/test/engine/fake_model_worker.h
index c85b666c657dfebb4b019f019343fd878637447e..beb54004c3d7dc118a1aea0a77009a19d2594cae 100644
--- a/sync/test/engine/fake_model_worker.h
+++ b/sync/test/engine/fake_model_worker.h
@@ -22,15 +22,14 @@ class FakeModelWorker : public ModelSafeWorker, public base::NonThreadSafe {
   explicit FakeModelWorker(ModelSafeGroup group);
 
   // ModelSafeWorker implementation.
-  virtual void RegisterForLoopDestruction() override;
-  virtual ModelSafeGroup GetModelSafeGroup() override;
+  void RegisterForLoopDestruction() override;
+  ModelSafeGroup GetModelSafeGroup() override;
 
  protected:
-  virtual SyncerError DoWorkAndWaitUntilDoneImpl(
-      const WorkCallback& work) override;
+  SyncerError DoWorkAndWaitUntilDoneImpl(const WorkCallback& work) override;
 
  private:
-  virtual ~FakeModelWorker();
+  ~FakeModelWorker() override;
 
   const ModelSafeGroup group_;