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

ui/display/chromeos/x11/display_snapshot_x11.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 UI_DISPLAY_CHROMEOS_X11_DISPLAY_SNAPSHOT_X11_H_
 #define UI_DISPLAY_CHROMEOS_X11_DISPLAY_SNAPSHOT_X11_H_
 
 #include "ui/display/display_export.h"
 #include "ui/display/types/display_snapshot.h"
 
@@ skipping 12 matching lines @@
                      DisplayConnectionType type,
                      bool is_aspect_preserving_scaling,
                      bool has_overscan,
                      std::string display_name,
                      const std::vector<const DisplayMode*>& modes,
                      const DisplayMode* current_mode,
                      const DisplayMode* native_mode,
                      RROutput output,
                      RRCrtc crtc,
                      int index);
-  virtual ~DisplaySnapshotX11();
+  ~DisplaySnapshotX11() override;
 
   RROutput output() const { return output_; }
   RRCrtc crtc() const { return crtc_; }
   int index() const { return index_; }
 
   // DisplaySnapshot overrides:
-  virtual std::string ToString() const override;
+  std::string ToString() const override;
 
  private:
   RROutput output_;
 
   // CRTC that should be used for this output. Not necessarily the CRTC
   // that XRandR reports is currently being used.
   RRCrtc crtc_;
 
   // This output's index in the array returned by XRandR. Stable even as
   // outputs are connected or disconnected.
   int index_;
 
   DISALLOW_COPY_AND_ASSIGN(DisplaySnapshotX11);
 };
 
 }  // namespace ui
 
 #endif  // UI_DISPLAY_CHROMEOS_X11_DISPLAY_SNAPSHOT_X11_H_