Add null check on navigation bar visibility

When there are hardware keys getNavigationBarView() returns null,
this just checks before setting the visibility.

Bug: 14491311
Change-Id: I2ea8b62b1dfe05ca09636870b37dff184730369e
diff --git a/packages/SystemUI/src/com/android/systemui/statusbar/phone/StatusBarKeyguardViewManager.java b/packages/SystemUI/src/com/android/systemui/statusbar/phone/StatusBarKeyguardViewManager.java
index c2595cf..db244fe 100644
--- a/packages/SystemUI/src/com/android/systemui/statusbar/phone/StatusBarKeyguardViewManager.java
+++ b/packages/SystemUI/src/com/android/systemui/statusbar/phone/StatusBarKeyguardViewManager.java
@@ -213,10 +213,12 @@
         } else {
             mContainer.setSystemUiVisibility(vis | View.STATUS_BAR_DISABLE_BACK);
         }
-        if (!(mShowing && !mOccluded) || mBouncer.isShowing()) {
-            mPhoneStatusBar.getNavigationBarView().setVisibility(View.VISIBLE);
-        } else {
-            mPhoneStatusBar.getNavigationBarView().setVisibility(View.GONE);
+        if (mPhoneStatusBar.getNavigationBarView() != null) {
+            if (!(mShowing && !mOccluded) || mBouncer.isShowing()) {
+                mPhoneStatusBar.getNavigationBarView().setVisibility(View.VISIBLE);
+            } else {
+                mPhoneStatusBar.getNavigationBarView().setVisibility(View.GONE);
+            }
         }
     }