Standardize usage of virtual/override/final specifiers.

ui/app_list/views/folder_background_view.h

Index: ui/app_list/views/folder_background_view.h
diff --git a/ui/app_list/views/folder_background_view.h b/ui/app_list/views/folder_background_view.h
index dd6c9dd58af5d5a3c98bdbbbb97715525b228622..00e06d742473951203068b5b6e9a542d6b2cb41b 100644
--- a/ui/app_list/views/folder_background_view.h
+++ b/ui/app_list/views/folder_background_view.h
@@ -24,7 +24,7 @@ class FolderBackgroundView : public views::View,
   };
 
   FolderBackgroundView();
-  virtual ~FolderBackgroundView();
+  ~FolderBackgroundView() override;
 
   // Updates the ink bubble's ShowState.
   void UpdateFolderContainerBubble(ShowState state);
@@ -38,10 +38,10 @@ class FolderBackgroundView : public views::View,
 
  private:
   // views::View overrides:
-  virtual void OnPaint(gfx::Canvas* canvas) override;
+  void OnPaint(gfx::Canvas* canvas) override;
 
   // ui::ImplicitAnimationObserver overrides:
-  virtual void OnImplicitAnimationsCompleted() override;
+  void OnImplicitAnimationsCompleted() override;
 
   AppListFolderView* folder_view_;
   ShowState show_state_;