Standardize usage of virtual/override/final in extensions/

extensions/browser/api/system_storage/storage_info_provider.h

 // Copyright 2013 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 EXTENSIONS_BROWSER_API_SYSTEM_STORAGE_STORAGE_INFO_PROVIDER_H_
 #define EXTENSIONS_BROWSER_API_SYSTEM_STORAGE_STORAGE_INFO_PROVIDER_H_
 
 #include <set>
 
 #include "base/lazy_instance.h"
@@ skipping 23 matching lines @@
 
 class StorageInfoProvider : public SystemInfoProvider {
  public:
   typedef base::Callback<void(const std::string&, double)>
       GetStorageFreeSpaceCallback;
 
   // Get the single shared instance of StorageInfoProvider.
   static StorageInfoProvider* Get();
 
   // SystemInfoProvider implementations
-  virtual void PrepareQueryOnUIThread() override;
-  virtual void InitializeProvider(
-      const base::Closure& do_query_info_callback) override;
+  void PrepareQueryOnUIThread() override;
+  void InitializeProvider(const base::Closure& do_query_info_callback) override;
 
   virtual double GetStorageFreeSpaceFromTransientIdOnFileThread(
       const std::string& transient_id);
 
   const StorageUnitInfoList& storage_unit_info_list() const;
 
   static void InitializeForTesting(scoped_refptr<StorageInfoProvider> provider);
 
  protected:
   StorageInfoProvider();
 
-  virtual ~StorageInfoProvider();
+  ~StorageInfoProvider() override;
 
   // Put all available storages' information into |info_|.
   void GetAllStoragesIntoInfoList();
 
   // The last information filled up by QueryInfo and is accessed on multiple
   // threads, but the whole class is being guarded by SystemInfoProvider base
   // class.
   //
   // |info_| is accessed on the UI thread while |is_waiting_for_completion_| is
   // false and on the sequenced worker pool while |is_waiting_for_completion_|
   // is true.
   StorageUnitInfoList info_;
 
  private:
   // SystemInfoProvider implementations.
   // Override to query the available capacity of all known storage devices on
   // the blocking pool, including fixed and removable devices.
-  virtual bool QueryInfo() override;
+  bool QueryInfo() override;
 
   static base::LazyInstance<scoped_refptr<StorageInfoProvider> > provider_;
 
   DISALLOW_COPY_AND_ASSIGN(StorageInfoProvider);
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_BROWSER_API_SYSTEM_STORAGE_STORAGE_INFO_PROVIDER_H_