Standardize usage of virtual/override/final specifiers.

ash/accelerators/exit_warning_handler.cc

Index: ash/accelerators/exit_warning_handler.cc
diff --git a/ash/accelerators/exit_warning_handler.cc b/ash/accelerators/exit_warning_handler.cc
index 275dc5ab9ed5e1634ec470f9a5e36d6e47344f01..21e4aff3abe5f837f14dd0e7b81b642ac0714ef9 100644
--- a/ash/accelerators/exit_warning_handler.cc
+++ b/ash/accelerators/exit_warning_handler.cc
@@ -68,11 +68,11 @@ class ExitWarningWidgetDelegateView : public views::WidgetDelegateView {
     SetLayoutManager(new views::FillLayout);
   }
 
-  virtual gfx::Size GetPreferredSize() const override {
+  gfx::Size GetPreferredSize() const override {
     return gfx::Size(width_, height_);
   }
 
-  virtual void OnPaint(gfx::Canvas* canvas) override {
+  void OnPaint(gfx::Canvas* canvas) override {
     SkPaint paint;
     paint.setStyle(SkPaint::kFill_Style);
     paint.setColor(kWindowBackgroundColor);
@@ -80,7 +80,7 @@ class ExitWarningWidgetDelegateView : public views::WidgetDelegateView {
     views::WidgetDelegateView::OnPaint(canvas);
   }
 
-  virtual void GetAccessibleState(ui::AXViewState* state) override {
+  void GetAccessibleState(ui::AXViewState* state) override {
     state->name = accessible_name_;
     state->role = ui::AX_ROLE_ALERT;
   }