Standardize usage of virtual/override/final specifiers.

ui/views/focus/external_focus_tracker.h

Index: ui/views/focus/external_focus_tracker.h
diff --git a/ui/views/focus/external_focus_tracker.h b/ui/views/focus/external_focus_tracker.h
index 3cfacb3baf52afb9fc17aa7d35e299469ff1d4a6..3fec0fd45c370ac245a23582c69c30b2db9c3a7d 100644
--- a/ui/views/focus/external_focus_tracker.h
+++ b/ui/views/focus/external_focus_tracker.h
@@ -29,13 +29,11 @@ class ViewStorage;
 class VIEWS_EXPORT ExternalFocusTracker : public FocusChangeListener {
  public:
   ExternalFocusTracker(View* parent_view, FocusManager* focus_manager);
-  virtual ~ExternalFocusTracker();
+  ~ExternalFocusTracker() override;
 
   // FocusChangeListener:
-  virtual void OnWillChangeFocus(View* focused_before,
-                                 View* focused_now) override;
-  virtual void OnDidChangeFocus(View* focused_before,
-                                View* focused_now) override;
+  void OnWillChangeFocus(View* focused_before, View* focused_now) override;
+  void OnDidChangeFocus(View* focused_before, View* focused_now) override;
 
   // Focuses last focused view which is not a child of parent view and is not
   // parent view itself. Returns true if focus for a view was requested, false