Fix the battery icon on the battery page when low battery

Check power-saving state for drawing the battery icon on the battery page.
It will draw red + icon as status-bar did when battery saver is on.

Change-Id: Iee4a17c8e5cb3c8ee5d978eb23e3980597d09a1c
Fixes: 77150820
Test: Manual test, atest BatteryMeterViewTest BatteryHeaderPreferenceControllerTest

src/com/android/settings/fuelgauge/BatteryMeterView.java

@@ -37,6 +37,7 @@ public class BatteryMeterView extends ImageView {
     ColorFilter mErrorColorFilter;
     @VisibleForTesting
     ColorFilter mAccentColorFilter;
+    private boolean mPowerSaveEnabled;
 
     public BatteryMeterView(Context context) {
         this(context, null, 0);
@@ -73,6 +74,15 @@ public class BatteryMeterView extends ImageView {
         }
     }
 
+    public void setPowerSave(boolean powerSave) {
+        mDrawable.setPowerSave(powerSave);
+        mPowerSaveEnabled = powerSave;
+    }
+
+    public boolean getPowerSave() {
+        return mPowerSaveEnabled;
+    }
+
     public int getBatteryLevel() {
         return mDrawable.getBatteryLevel();
     }