Merge "Guard potential null case in FullscreenTaskListener.releaseWindowDecor found in testing." into tm-qpr-dev

libs/WindowManager/Shell/src/com/android/wm/shell/fullscreen/FullscreenTaskListener.java

@@ -287,6 +287,9 @@ public class FullscreenTaskListener<T extends AutoCloseable>
     }
 
     private void releaseWindowDecor(T windowDecor) {
+        if (windowDecor == null) {
+            return;
+        }
         try {
             windowDecor.close();
         } catch (Exception e) {