C++11 override style change for athena

chromeos/accelerometer/accelerometer_reader.h

Index: chromeos/accelerometer/accelerometer_reader.h
diff --git a/chromeos/accelerometer/accelerometer_reader.h b/chromeos/accelerometer/accelerometer_reader.h
index 79821ac61479716f9cecdfb1b0913d8bce293867..3cf473f72cf44346c83714a3a9f2fdea6f0e4861 100644
--- a/chromeos/accelerometer/accelerometer_reader.h
+++ b/chromeos/accelerometer/accelerometer_reader.h
@@ -47,6 +47,8 @@ class CHROMEOS_EXPORT AccelerometerReader {
   // An interface to receive data from the AccelerometerReader.
   class Delegate {
    public:
+    virtual ~Delegate() {}
+
     virtual void HandleAccelerometerUpdate(
         const ui::AccelerometerUpdate& update) = 0;
   };