Called when a translucent activity over this activity is becoming opaque or another activity is being launched. Activities that override this method must call super.onVisibleBehindCanceled() or a SuperNotCalledException will be thrown.
When this method is called the activity has 500 msec to release any resources it may be using while visible in the background. If the activity has not returned from this method in 500 msec the system will destroy the activity and kill the process in order to recover the resources for another process. Otherwise Activity.OnStop will be called following return.