This gets invoked when the compass accuracy status changes from one value to another. It provides an integer value which is identical to the SensorManager class constants:
SensorManager
android.hardware.SensorManager.SENSOR_STATUS_NO_CONTACT
android.hardware.SensorManager.SENSOR_STATUS_UNRELIABLE
android.hardware.SensorManager.SENSOR_STATUS_ACCURACY_LOW
android.hardware.SensorManager.SENSOR_STATUS_ACCURACY_MEDIUM
android.hardware.SensorManager.SENSOR_STATUS_ACCURACY_HIGH
the new accuracy of this sensor, one of SensorManager.SENSOR_STATUS_*
SensorManager.SENSOR_STATUS_*