C++11 override style change for athena

athena/wm/window_list_provider_impl_unittest.cc

Index: athena/wm/window_list_provider_impl_unittest.cc
diff --git a/athena/wm/window_list_provider_impl_unittest.cc b/athena/wm/window_list_provider_impl_unittest.cc
index d3dd2859b26752d283f544a6bc9bc259f9d4e869..76d1dd6e2bc142a8f91aeaaec4377b1d8353dd93 100644
--- a/athena/wm/window_list_provider_impl_unittest.cc
+++ b/athena/wm/window_list_provider_impl_unittest.cc
@@ -64,7 +64,7 @@ class WindowListObserver : public WindowListProviderObserver {
       : calls_(0), window_removal_calls_(0), provider_(provider) {
     provider_->AddObserver(this);
   }
-  virtual ~WindowListObserver() {
+  ~WindowListObserver() override {
     provider_->RemoveObserver(this);
   }
 
@@ -72,11 +72,11 @@ class WindowListObserver : public WindowListProviderObserver {
   int window_removal_calls() const { return window_removal_calls_; }
 
   // WindowListProviderObserver:
-  virtual void OnWindowStackingChanged() override {
+  void OnWindowStackingChanged() override {
     calls_++;
   }
 
-  virtual void OnWindowRemoved(aura::Window* removed_window,
+  void OnWindowRemoved(aura::Window* removed_window,
                                int index) override {
     window_removal_calls_++;
   }