Standardize usage of virtual/override/final specifiers.

ash/wm/immersive_fullscreen_controller.cc

Index: ash/wm/immersive_fullscreen_controller.cc
diff --git a/ash/wm/immersive_fullscreen_controller.cc b/ash/wm/immersive_fullscreen_controller.cc
index 172d5720882eeb5f82c5bf6254303f1c7cd4bf25..9b3c01c4be77272ccbb6f26c6ed102b41e86f760 100644
--- a/ash/wm/immersive_fullscreen_controller.cc
+++ b/ash/wm/immersive_fullscreen_controller.cc
@@ -132,7 +132,7 @@ class ImmersiveFullscreenController::BubbleManager
     : public aura::WindowObserver {
  public:
   explicit BubbleManager(ImmersiveFullscreenController* controller);
-  virtual ~BubbleManager();
+  ~BubbleManager() override;
 
   // Start / stop observing changes to |bubble|'s visibility.
   void StartObserving(aura::Window* bubble);
@@ -143,9 +143,8 @@ class ImmersiveFullscreenController::BubbleManager
   void UpdateRevealedLock();
 
   // aura::WindowObserver overrides:
-  virtual void OnWindowVisibilityChanged(aura::Window* window,
-                                         bool visible) override;
-  virtual void OnWindowDestroying(aura::Window* window) override;
+  void OnWindowVisibilityChanged(aura::Window* window, bool visible) override;
+  void OnWindowDestroying(aura::Window* window) override;
 
   ImmersiveFullscreenController* controller_;