Move battery percent constant to Settings

This switch is moving to system settings so it should also be declared
by Settings. Also changed the constant's name to make sense in the
System context.

Test: runtest systemui
Bug: 32539932
Change-Id: I7cce21b50702f31465328dd8faed3fbac47528ea
diff --git a/packages/SystemUI/src/com/android/systemui/BatteryMeterView.java b/packages/SystemUI/src/com/android/systemui/BatteryMeterView.java
index ee8641b..14f2c4a 100644
--- a/packages/SystemUI/src/com/android/systemui/BatteryMeterView.java
+++ b/packages/SystemUI/src/com/android/systemui/BatteryMeterView.java
@@ -15,6 +15,8 @@
  */
 package com.android.systemui;
 
+import static android.provider.Settings.System.SHOW_BATTERY_PERCENT;
+
 import android.content.Context;
 import android.content.res.Resources;
 import android.content.res.TypedArray;
@@ -50,8 +52,6 @@
 public class BatteryMeterView extends LinearLayout implements
         BatteryStateChangeCallback, Tunable, DarkReceiver, ConfigurationListener {
 
-    public static final String SHOW_PERCENT_SETTING = "status_bar_show_battery_percent";
-
     private final BatteryMeterDrawableBase mDrawable;
     private final String mSlotBattery;
     private final ImageView mBatteryIconView;
@@ -129,7 +129,7 @@
         mBatteryController = Dependency.get(BatteryController.class);
         mBatteryController.addCallback(this);
         getContext().getContentResolver().registerContentObserver(
-                Settings.System.getUriFor(SHOW_PERCENT_SETTING), false, mSettingObserver);
+                Settings.System.getUriFor(SHOW_BATTERY_PERCENT), false, mSettingObserver);
         updateShowPercent();
         Dependency.get(TunerService.class).addTunable(this, StatusBarIconController.ICON_BLACKLIST);
         Dependency.get(ConfigurationController.class).addCallback(this);
@@ -175,7 +175,7 @@
     private void updateShowPercent() {
         final boolean showing = mBatteryPercentView != null;
         if (0 != Settings.System.getInt(getContext().getContentResolver(),
-                BatteryMeterView.SHOW_PERCENT_SETTING, 0) || mForceShowPercent) {
+                SHOW_BATTERY_PERCENT, 0) || mForceShowPercent) {
             if (!showing) {
                 mBatteryPercentView = loadPercentView();
                 if (mTextColor != 0) mBatteryPercentView.setTextColor(mTextColor);