Avoid NPE when mRoot is null.

Bug: 14162288
Change-Id: I36793d706ab1d29576f536562a0c06f7805a0d50
diff --git a/packages/SystemUI/src/com/android/systemui/statusbar/phone/KeyguardBouncer.java b/packages/SystemUI/src/com/android/systemui/statusbar/phone/KeyguardBouncer.java
index f2054a2..cf31b44 100644
--- a/packages/SystemUI/src/com/android/systemui/statusbar/phone/KeyguardBouncer.java
+++ b/packages/SystemUI/src/com/android/systemui/statusbar/phone/KeyguardBouncer.java
@@ -83,7 +83,7 @@
     }
 
     public void onScreenTurnedOff() {
-        if (mKeyguardView != null && mRoot.getVisibility() == View.VISIBLE) {
+        if (mKeyguardView != null && mRoot != null && mRoot.getVisibility() == View.VISIBLE) {
             mKeyguardView.onPause();
         }
     }