Merge "Fix NPE in TvPipController" into sc-dev am: 03b61d22b6

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/15156230

Change-Id: Ie73828ded3e77c3c1f371d45033234639562673b

libs/WindowManager/Shell/src/com/android/wm/shell/pip/tv/TvPipController.java

@@ -279,7 +279,7 @@ public class TvPipController implements PipTransitionController.PipTransitionCal
     private void checkIfPinnedTaskAppeared() {
         final TaskInfo pinnedTask = getPinnedTaskInfo();
         if (DEBUG) Log.d(TAG, "checkIfPinnedTaskAppeared(), task=" + pinnedTask);
-        if (pinnedTask == null) return;
+        if (pinnedTask == null || pinnedTask.topActivity == null) return;
         mPinnedTaskId = pinnedTask.taskId;
         setState(STATE_PIP);