Update {virtual,override} to follow C++11 style in chrome.

chrome/browser/extensions/display_info_provider_win.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_EXTENSIONS_DISPLAY_INFO_PROVIDER_WIN_H_
 #define CHROME_BROWSER_EXTENSIONS_DISPLAY_INFO_PROVIDER_WIN_H_
 
 #include "extensions/browser/api/system_display/display_info_provider.h"
 
 namespace extensions {
 
 class DisplayInfoProviderWin : public DisplayInfoProvider {
  public:
   DisplayInfoProviderWin();
-  virtual ~DisplayInfoProviderWin();
+  ~DisplayInfoProviderWin() override;
 
   // DisplayInfoProvider implementation.
-  virtual bool SetInfo(const std::string& display_id,
-                       const core_api::system_display::DisplayProperties& info,
-                       std::string* error) override;
-  virtual void UpdateDisplayUnitInfoForPlatform(
+  bool SetInfo(const std::string& display_id,
+               const core_api::system_display::DisplayProperties& info,
+               std::string* error) override;
+  void UpdateDisplayUnitInfoForPlatform(
       const gfx::Display& display,
       core_api::system_display::DisplayUnitInfo* unit) override;
-  virtual gfx::Screen* GetActiveScreen() override;
+  gfx::Screen* GetActiveScreen() override;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(DisplayInfoProviderWin);
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_DISPLAY_INFO_PROVIDER_WIN_H_