Standardize usage of virtual/override/final specifiers.

ash/system/tray/tray_bar_button_with_title.cc

Index: ash/system/tray/tray_bar_button_with_title.cc
diff --git a/ash/system/tray/tray_bar_button_with_title.cc b/ash/system/tray/tray_bar_button_with_title.cc
index 212a7c9cb4a80ef1d45894829a8a697abd594b7a..1ad17cc8d69fcd6419512db46109d3881ec8cd9d 100644
--- a/ash/system/tray/tray_bar_button_with_title.cc
+++ b/ash/system/tray/tray_bar_button_with_title.cc
@@ -37,10 +37,10 @@ class TrayBarButtonWithTitle::TrayBarButton : public views::View {
       bar_disabled_images_(bar_disabled_images),
       painter_(new views::HorizontalPainter(bar_active_images_)){
   }
-  virtual ~TrayBarButton() {}
+  ~TrayBarButton() override {}
 
   // Overriden from views::View:
-  virtual void OnPaint(gfx::Canvas* canvas) override {
+  void OnPaint(gfx::Canvas* canvas) override {
     painter_->Paint(canvas, size());
   }