Standardize usage of virtual/override/final specifiers.

ash/system/tray/default_system_tray_delegate.cc

 // 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.
 
 #include "ash/system/tray/default_system_tray_delegate.h"
 
 #include <string>
 
 #include "ash/session/session_state_delegate.h"
 #include "ash/shell.h"
 #include "ash/volume_control_delegate.h"
 #include "base/message_loop/message_loop.h"
 #include "base/time/time.h"
 
 namespace ash {
 
 namespace {
 
 class DefaultVolumnControlDelegate : public VolumeControlDelegate {
  public:
   DefaultVolumnControlDelegate() {}
-  virtual ~DefaultVolumnControlDelegate() {}
+  ~DefaultVolumnControlDelegate() override {}
 
-  virtual bool HandleVolumeMute(const ui::Accelerator& accelerator) override {
+  bool HandleVolumeMute(const ui::Accelerator& accelerator) override {
     return true;
   }
-  virtual bool HandleVolumeDown(const ui::Accelerator& accelerator) override {
+  bool HandleVolumeDown(const ui::Accelerator& accelerator) override {
     return true;
   }
-  virtual bool HandleVolumeUp(const ui::Accelerator& accelerator) override {
+  bool HandleVolumeUp(const ui::Accelerator& accelerator) override {
     return true;
   }
 
  private:
   DISALLOW_COPY_AND_ASSIGN(DefaultVolumnControlDelegate);
 };
 
 }  // namespace
 
 DefaultSystemTrayDelegate::DefaultSystemTrayDelegate()
@@ skipping 239 matching lines @@
 
 void DefaultSystemTrayDelegate::AddCustodianInfoTrayObserver(
     CustodianInfoTrayObserver* observer) {
 }
 
 void DefaultSystemTrayDelegate::RemoveCustodianInfoTrayObserver(
     CustodianInfoTrayObserver* observer) {
 }
 
 }  // namespace ash