C++11 override style change for athena

athena/content/app_activity_browsertest.cc

Index: athena/content/app_activity_browsertest.cc
diff --git a/athena/content/app_activity_browsertest.cc b/athena/content/app_activity_browsertest.cc
index 22a4c1abbe78c142a17b52c7c9ea9a6a1e800a95..17cc893d5c6f8350c2ede3fbe100a30575c14211 100644
--- a/athena/content/app_activity_browsertest.cc
+++ b/athena/content/app_activity_browsertest.cc
@@ -23,15 +23,15 @@ const char kTestUrl[] = "chrome:about";
 class AppActivityBrowserTest : public AthenaAppBrowserTest {
  public:
   AppActivityBrowserTest() {}
-  virtual ~AppActivityBrowserTest() {}
+  ~AppActivityBrowserTest() override {}
 
   // AthenaAppBrowserTest:
-  virtual void SetUpOnMainThread() override {
+  void SetUpOnMainThread() override {
     tracker_.reset(new ActivityLifetimeTracker);
     AthenaAppBrowserTest::SetUpOnMainThread();
   }
 
-  virtual void TearDownOnMainThread() override {
+  void TearDownOnMainThread() override {
     tracker_.reset();
     AthenaAppBrowserTest::TearDownOnMainThread();
   }