title: Can't correctly release PowerManager.WakeLock
body: <p>I'm using <code>PowerManager.WakeLock</code> for <code>Sensor.TYPE_LIGHT</code> in <code>Activity</code>.
  It works well but when i'm closing/went to other <code>Activity</code> <code>SensorEventListener</code> keep turn on/off screen if get sensor changes.</p>
  
  <p>Code sample</p>
  
  <pre><code>    SensorManager mSensorManager = (SensorManager) getSystemService(SENSOR_SERVICE);
      Sensor mLightSensor = mSensorManager.getDefaultSensor(Sensor.TYPE_LIGHT);
      PowerManager mPowerManager = (PowerManager) getSystemService(Context.POWER_SERVICE);
      PowerManager.WakeLock mWakeLock = mPowerManager.newWakeLock(PowerManager.PROXIMITY_SCREEN_OFF_WAKE_LOCK, "tag");
  </code></pre>
  
  <p><code>SensorEventListener</code> interface method</p>
  
  <pre><code>@Override
  public void onSensorChanged(SensorEvent event) {
      float[] lux = event.values;
  
      if (lux[0] &lt;= 200) {
          mWakeLock.acquire();
      } else {
          if (mWakeLock.isHeld()) {
              mWakeLock.release();
          }
      }
  }
  </code></pre>
  
  <p><code>SensorManager</code> listener </p>
  
  <pre><code> @Override
  protected void onResume() {
      super.onResume();
      mSensorManager.registerListener(this, mLightSensor, SensorManager.SENSOR_DELAY_FASTEST);
  
  }
  
  @Override
  protected void onPause() {
      super.onPause();
      mSensorManager.unregisterListener(this, mLightSensor);
  
  }
  
  @Override
  protected void onDestroy() {
      super.onDestroy();
      if (mWakeLock.isHeld()) {
          mWakeLock.release();
      }
  
  }
  </code></pre>
  
  <p>So how to correctly release and disable <code>WakeLock</code>. Thanks in advance.</p>