Fix lockscreen

Bug: 5391404

Change-Id: I021a37705b72ab1990f7651fecbe743a8af4e372

Author: Justin Ho

policy/src/com/android/internal/policy/impl/LockPatternKeyguardView.java

@@ -996,10 +996,14 @@ private void initializeFaceLockAreaView(View view) {
     public boolean handleMessage(Message msg) {
         switch (msg.what) {
         case MSG_SHOW_FACELOCK_AREA_VIEW:
-            mFaceLockAreaView.setVisibility(View.VISIBLE);
+            if (mFaceLockAreaView != null) {
+                mFaceLockAreaView.setVisibility(View.VISIBLE);
+            }
             break;
         case MSG_HIDE_FACELOCK_AREA_VIEW:
-            mFaceLockAreaView.setVisibility(View.GONE);
+            if (mFaceLockAreaView != null) {
+                mFaceLockAreaView.setVisibility(View.GONE);
+            }
             break;
         default:
             Log.w(TAG, "Unhandled message");