Check if the display is attached when updating config

The display might not be added yet or be already detached when
config is updated.

Bug: 32983305
Test: android.media.cts.EncodeVirtualDisplayWithCompositionTest
Test: #testVirtualDisplayRecycles
Change-Id: I3b0e52e8ebb93a57ab6b0e80c0599db33ce2ae03
diff --git a/services/core/java/com/android/server/am/ActivityStackSupervisor.java b/services/core/java/com/android/server/am/ActivityStackSupervisor.java
index eb34669..48108fe 100644
--- a/services/core/java/com/android/server/am/ActivityStackSupervisor.java
+++ b/services/core/java/com/android/server/am/ActivityStackSupervisor.java
@@ -3561,6 +3561,11 @@
         }
     }
 
+    /** Check if display with specified id is added to the list. */
+    boolean isDisplayAdded(int displayId) {
+        return mActivityDisplays.get(displayId) != null;
+    }
+
     private void calculateDefaultMinimalSizeOfResizeableTasks(ActivityDisplay display) {
         mDefaultMinSizeOfResizeableTask =
                 mService.mContext.getResources().getDimensionPixelSize(