Enable auto-brightness adjustment feature with system prop.

This feature is experimental and disabled by default.

Change-Id: I9c3c77d6d207ceec65e0babc7915db8d439d5da2
diff --git a/src/com/android/settings/BrightnessPreference.java b/src/com/android/settings/BrightnessPreference.java
index 858d50f..2cf6b43 100644
--- a/src/com/android/settings/BrightnessPreference.java
+++ b/src/com/android/settings/BrightnessPreference.java
@@ -39,7 +39,8 @@
 public class BrightnessPreference extends SeekBarDialogPreference implements
         SeekBar.OnSeekBarChangeListener, CheckBox.OnCheckedChangeListener {
     // If true, enables the use of the screen auto-brightness adjustment setting.
-    private static final boolean USE_SCREEN_AUTO_BRIGHTNESS_ADJUSTMENT = false;
+    private static final boolean USE_SCREEN_AUTO_BRIGHTNESS_ADJUSTMENT =
+            PowerManager.useScreenAutoBrightnessAdjustmentFeature();
 
     private final int mScreenBrightnessMinimum;
     private final int mScreenBrightnessMaximum;