Camera: Fix null pointer access

If a device is rebooted then the RecentTasks contains task list but
topActivityInfo could be null. In this case, if a camera device is
opened from a process without activity then CameraServiceProxy could
access null topActivityInfo.

Bug: 272428586
Test: Manual test with the OEM attention service
Change-Id: I9a9f42e8954d72e74c74f26ad5a690bcdd3a4cbc
diff --git a/services/core/java/com/android/server/camera/CameraServiceProxy.java b/services/core/java/com/android/server/camera/CameraServiceProxy.java
index aec60de..96fcd9d 100644
--- a/services/core/java/com/android/server/camera/CameraServiceProxy.java
+++ b/services/core/java/com/android/server/camera/CameraServiceProxy.java
@@ -487,7 +487,8 @@
 
             if ((recentTasks != null) && (!recentTasks.getList().isEmpty())) {
                 for (ActivityManager.RecentTaskInfo task : recentTasks.getList()) {
-                    if (packageName.equals(task.topActivityInfo.packageName)) {
+                    if (task.topActivityInfo != null && packageName.equals(
+                            task.topActivityInfo.packageName)) {
                         taskInfo = new TaskInfo();
                         taskInfo.frontTaskId = task.taskId;
                         taskInfo.isResizeable =