C++11 override style change for athena

athena/content/app_registry_impl.cc

Index: athena/content/app_registry_impl.cc
diff --git a/athena/content/app_registry_impl.cc b/athena/content/app_registry_impl.cc
index 0e750f30ddf292f02f2bcf210425dbba7a94e2a5..a7e11e51dbaa8b93e330fbb9d25705ae48be4b83 100644
--- a/athena/content/app_registry_impl.cc
+++ b/athena/content/app_registry_impl.cc
@@ -12,16 +12,16 @@ namespace athena {
 class AppRegistryImpl : public AppRegistry {
  public:
   AppRegistryImpl();
-  virtual ~AppRegistryImpl();
+  ~AppRegistryImpl() override;
 
   // AppRegistry:
-  virtual AppActivityRegistry* GetAppActivityRegistry(
+  AppActivityRegistry* GetAppActivityRegistry(
       const std::string& app_id,
       content::BrowserContext* browser_context) override;
-  virtual int NumberOfApplications() const override { return app_list_.size(); }
+  int NumberOfApplications() const override { return app_list_.size(); }
 
  private:
-  virtual void RemoveAppActivityRegistry(
+  void RemoveAppActivityRegistry(
       AppActivityRegistry* registry) override;
 
   std::vector<AppActivityRegistry*> app_list_;