Check nullity of ResultReceiver

Bug: 182164496
Test: N/A
Change-Id: I96bdef1c79f8f91d33d6a6a734bc94e162a5ea33
(cherry picked from commit 2d12628ecc)

apex/media/framework/java/android/media/MediaSession2.java

@@ -469,7 +469,9 @@ public class MediaSession2 implements AutoCloseable {
         }
         mCallbackExecutor.execute(() -> {
             if (!controllerInfo.removeRequestedCommandSeqNumber(seq)) {
-                resultReceiver.send(RESULT_INFO_SKIPPED, null);
+                if (resultReceiver != null) {
+                    resultReceiver.send(RESULT_INFO_SKIPPED, null);
+                }
                 return;
             }
             Session2Command.Result result = mCallback.onSessionCommand(