Update {virtual,override,final} to follow C++11 style in ash.

ash/display/projecting_observer_chromeos_unittest.cc

Index: ash/display/projecting_observer_chromeos_unittest.cc
diff --git a/ash/display/projecting_observer_chromeos_unittest.cc b/ash/display/projecting_observer_chromeos_unittest.cc
index 89f747768d592365f315607ca7a5e0f37972ed7d..ebc888e2da50d66e3831b0f8bc6f0f2648fc38d6 100644
--- a/ash/display/projecting_observer_chromeos_unittest.cc
+++ b/ash/display/projecting_observer_chromeos_unittest.cc
@@ -40,7 +40,7 @@ class ProjectingObserverTest : public testing::Test {
  public:
   ProjectingObserverTest() : observer_(&fake_power_client_) {}
 
-  virtual ~ProjectingObserverTest() {}
+  ~ProjectingObserverTest() override {}
 
  protected:
   chromeos::FakePowerManagerClient fake_power_client_;