Standardize usage of virtual/override/final specifiers.

ash/ime/candidate_window_view.h

Index: ash/ime/candidate_window_view.h
diff --git a/ash/ime/candidate_window_view.h b/ash/ime/candidate_window_view.h
index 4cbc5b71db588d80cde272983434b415924768f8..99800f8efb831cebf220248cf5a6697b3df504b6 100644
--- a/ash/ime/candidate_window_view.h
+++ b/ash/ime/candidate_window_view.h
@@ -29,7 +29,7 @@ class ASH_EXPORT CandidateWindowView : public views::BubbleDelegateView,
   };
 
   explicit CandidateWindowView(gfx::NativeView parent);
-  virtual ~CandidateWindowView();
+  ~CandidateWindowView() override;
   views::Widget* InitWidget();
 
   // Adds the given observer. The ownership is not transferred.
@@ -74,8 +74,7 @@ class ASH_EXPORT CandidateWindowView : public views::BubbleDelegateView,
   friend class CandidateWindowViewTest;
 
   // Overridden from views::ButtonListener:
-  virtual void ButtonPressed(views::Button* sender,
-                             const ui::Event& event) override;
+  void ButtonPressed(views::Button* sender, const ui::Event& event) override;
 
   void SelectCandidateAt(int index_in_page);
   void UpdateVisibility();