Standardize usage of virtual/override/final specifiers.

ui/app_list/views/page_switcher.cc

Index: ui/app_list/views/page_switcher.cc
diff --git a/ui/app_list/views/page_switcher.cc b/ui/app_list/views/page_switcher.cc
index 4ab6d6c481d7ceca274c37ca7e5c337402f2c0dd..3a6942fcc61a45588868ee61735301949f29ddf6 100644
--- a/ui/app_list/views/page_switcher.cc
+++ b/ui/app_list/views/page_switcher.cc
@@ -36,7 +36,7 @@ class PageSwitcherButton : public views::CustomButton {
         button_width_(kMaxButtonWidth),
         selected_range_(0) {
   }
-  virtual ~PageSwitcherButton() {}
+  ~PageSwitcherButton() override {}
 
   void SetSelectedRange(double selected_range) {
     if (selected_range_ == selected_range)
@@ -49,11 +49,11 @@ class PageSwitcherButton : public views::CustomButton {
   void set_button_width(int button_width) { button_width_ = button_width; }
 
   // Overridden from views::View:
-  virtual gfx::Size GetPreferredSize() const override {
+  gfx::Size GetPreferredSize() const override {
     return gfx::Size(button_width_, kButtonHeight);
   }
 
-  virtual void OnPaint(gfx::Canvas* canvas) override {
+  void OnPaint(gfx::Canvas* canvas) override {
     if (state() == STATE_HOVERED)
       PaintButton(canvas, kPagerHoverColor);
     else