Standardize usage of virtual/override/final specifiers.

chrome/browser/ui/libgtk2ui/gtk2_border.cc

Index: chrome/browser/ui/libgtk2ui/gtk2_border.cc
diff --git a/chrome/browser/ui/libgtk2ui/gtk2_border.cc b/chrome/browser/ui/libgtk2ui/gtk2_border.cc
index ac9d08842bdd1962581181ac7169e6a067ef2c65..daa2c88c1db8cc5d2bf5f4238c3678159b1c0000 100644
--- a/chrome/browser/ui/libgtk2ui/gtk2_border.cc
+++ b/chrome/browser/ui/libgtk2ui/gtk2_border.cc
@@ -44,10 +44,9 @@ class ButtonImageSkiaSource : public gfx::ImageSkiaSource {
         size_(size) {
   }
 
-  virtual ~ButtonImageSkiaSource() {
-  }
+  ~ButtonImageSkiaSource() override {}
 
-  virtual gfx::ImageSkiaRep GetImageForScale(float scale) override {
+  gfx::ImageSkiaRep GetImageForScale(float scale) override {
     int w = size_.width() * scale;
     int h = size_.height() * scale;
     return gfx::ImageSkiaRep(