NavigationBarView: Fix NPE in Drawable.setVisible()

Bug: 17495735
Change-Id: I9d5ed5a324ae5c08ea0c225104c41b44462aff22
diff --git a/packages/SystemUI/src/com/android/systemui/statusbar/phone/NavigationBarView.java b/packages/SystemUI/src/com/android/systemui/statusbar/phone/NavigationBarView.java
index e0319f0..4b06cd0 100644
--- a/packages/SystemUI/src/com/android/systemui/statusbar/phone/NavigationBarView.java
+++ b/packages/SystemUI/src/com/android/systemui/statusbar/phone/NavigationBarView.java
@@ -507,17 +507,6 @@
         }
     }
 
-    @Override
-    public void setVisibility(int visibility) {
-        super.setVisibility(visibility);
-        boolean visible = visibility == View.VISIBLE;
-        getBackButton().getBackground().setVisible(visible, false /* restart */);
-        getHomeButton().getBackground().setVisible(visible, false /* restart */);
-        getRecentsButton().getBackground().setVisible(visible, false /* restart */);
-        getMenuButton().getBackground().setVisible(visible, false /* restart */);
-        getImeSwitchButton().getBackground().setVisible(visible, false /* restart */);
-    }
-
     /*
     @Override
     protected void onLayout (boolean changed, int left, int top, int right, int bottom) {