Standardize usage of virtual/override/final in chrome/browser/sync/

chrome/browser/sync/glue/invalidation_adapter.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CHROME_BROWSER_SYNC_GLUE_INVALIDATION_ADAPTER_H_
 #define CHROME_BROWSER_SYNC_GLUE_INVALIDATION_ADAPTER_H_
 
 #include "components/invalidation/invalidation.h"
 #include "sync/internal_api/public/base/invalidation_interface.h"
 
 namespace browser_sync {
 
 // Wraps a syncer::Invalidation in the syncer::InvalidationInterface.
 class InvalidationAdapter : public syncer::InvalidationInterface {
  public:
   explicit InvalidationAdapter(const syncer::Invalidation& invalidation);
-  virtual ~InvalidationAdapter();
+  ~InvalidationAdapter() override;
 
   // Implementation of InvalidationInterface.
-  virtual bool IsUnknownVersion() const override;
-  virtual const std::string& GetPayload() const override;
-  virtual int64 GetVersion() const override;
-  virtual void Acknowledge() override;
-  virtual void Drop() override;
+  bool IsUnknownVersion() const override;
+  const std::string& GetPayload() const override;
+  int64 GetVersion() const override;
+  void Acknowledge() override;
+  void Drop() override;
 
  private:
   syncer::Invalidation invalidation_;
 };
 
 }  // namespace browser_sync
 
 #endif  // CHROME_BROWSER_SYNC_GLUE_INVALIDATION_ADAPTER_H_