Fix NPE.

Bug: 5192200
Change-Id: Ifd869f92969016ea9c3ff9c5fa0a2a0f197c6cbf
diff --git a/packages/SystemUI/src/com/android/systemui/statusbar/phone/PhoneStatusBar.java b/packages/SystemUI/src/com/android/systemui/statusbar/phone/PhoneStatusBar.java
index 7a563c7..fe9eceb 100644
--- a/packages/SystemUI/src/com/android/systemui/statusbar/phone/PhoneStatusBar.java
+++ b/packages/SystemUI/src/com/android/systemui/statusbar/phone/PhoneStatusBar.java
@@ -1505,7 +1505,9 @@
                 if (lightsOut) {
                     animateCollapse();
                 }
-                mNavigationBarView.setLowProfile(lightsOut);
+                if (mNavigationBarView != null) {
+                    mNavigationBarView.setLowProfile(lightsOut);
+                }
             }
 
             notifyUiVisibilityChanged();