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

ash/system/chromeos/settings/tray_settings.cc

Index: ash/system/chromeos/settings/tray_settings.cc
diff --git a/ash/system/chromeos/settings/tray_settings.cc b/ash/system/chromeos/settings/tray_settings.cc
index 8b4c6c9dfa4e310e1b004d662fd03625ae5d84d7..c7f9039e1fcb4498f6eea057265c7c417ad12a40 100644
--- a/ash/system/chromeos/settings/tray_settings.cc
+++ b/ash/system/chromeos/settings/tray_settings.cc
@@ -71,12 +71,10 @@ class SettingsDefaultView : public ActionableView,
     }
   }
 
-  virtual ~SettingsDefaultView() {
-    PowerStatus::Get()->RemoveObserver(this);
-  }
+  ~SettingsDefaultView() override { PowerStatus::Get()->RemoveObserver(this); }
 
   // Overridden from ash::ActionableView.
-  virtual bool PerformAction(const ui::Event& event) override {
+  bool PerformAction(const ui::Event& event) override {
     bool userAddingRunning = ash::Shell::GetInstance()
                                  ->session_state_delegate()
                                  ->IsInSecondaryLoginScreen();
@@ -90,7 +88,7 @@ class SettingsDefaultView : public ActionableView,
   }
 
   // Overridden from views::View.
-  virtual void Layout() override {
+  void Layout() override {
     views::View::Layout();
 
     if (label_ && power_status_view_) {
@@ -105,13 +103,13 @@ class SettingsDefaultView : public ActionableView,
   }
 
   // Overridden from views::View.
-  virtual void ChildPreferredSizeChanged(views::View* child) override {
+  void ChildPreferredSizeChanged(views::View* child) override {
     views::View::ChildPreferredSizeChanged(child);
     Layout();
   }
 
   // Overridden from PowerStatus::Observer.
-  virtual void OnPowerStatusChanged() override {
+  void OnPowerStatusChanged() override {
     if (!PowerStatus::Get()->IsBatteryPresent())
       return;