Standardize usage of virtual/override/final specifiers.

ui/views/background.cc

Index: ui/views/background.cc
diff --git a/ui/views/background.cc b/ui/views/background.cc
index d2d64bb6d70aa1d4ecd2b681ebbedf17404616f5..0fbd0ecbebe41adfce22806ba9395cc4dde17a5d 100644
--- a/ui/views/background.cc
+++ b/ui/views/background.cc
@@ -22,7 +22,7 @@ class SolidBackground : public Background {
     SetNativeControlColor(color);
   }
 
-  virtual void Paint(gfx::Canvas* canvas, View* view) const override {
+  void Paint(gfx::Canvas* canvas, View* view) const override {
     // Fill the background. Note that we don't constrain to the bounds as
     // canvas is already clipped for us.
     canvas->DrawColor(get_color());
@@ -39,13 +39,12 @@ class BackgroundPainter : public Background {
     DCHECK(painter);
   }
 
-  virtual ~BackgroundPainter() {
+  ~BackgroundPainter() override {
     if (owns_painter_)
       delete painter_;
   }
 
-
-  virtual void Paint(gfx::Canvas* canvas, View* view) const override {
+  void Paint(gfx::Canvas* canvas, View* view) const override {
     Painter::PaintPainterAt(canvas, painter_, view->GetLocalBounds());
   }