Standardize usage of virtual/override/final in sync/

sync/engine/all_status.h

Index: sync/engine/all_status.h
diff --git a/sync/engine/all_status.h b/sync/engine/all_status.h
index ba2dd74239e236613e71286acd8f0e6272d5b762..6eadc6dcad66a2459987b8e50a34db3b2672a3ba 100644
--- a/sync/engine/all_status.h
+++ b/sync/engine/all_status.h
@@ -38,15 +38,15 @@ class AllStatus : public SyncEngineEventListener {
   friend class ScopedStatusLock;
  public:
   AllStatus();
-  virtual ~AllStatus();
+  ~AllStatus() override;
 
   // SyncEngineEventListener implementation.
-  virtual void OnSyncCycleEvent(const SyncCycleEvent& event) override;
-  virtual void OnActionableError(const SyncProtocolError& error) override;
-  virtual void OnRetryTimeChanged(base::Time retry_time) override;
-  virtual void OnThrottledTypesChanged(ModelTypeSet throttled_types) override;
-  virtual void OnMigrationRequested(ModelTypeSet types) override;
-  virtual void OnProtocolEvent(const ProtocolEvent& event) override;
+  void OnSyncCycleEvent(const SyncCycleEvent& event) override;
+  void OnActionableError(const SyncProtocolError& error) override;
+  void OnRetryTimeChanged(base::Time retry_time) override;
+  void OnThrottledTypesChanged(ModelTypeSet throttled_types) override;
+  void OnMigrationRequested(ModelTypeSet types) override;
+  void OnProtocolEvent(const ProtocolEvent& event) override;
 
   SyncStatus status() const;