Null check on BroadcastRecord's receivers list.

Bug: 227729678
Test: adb shell "am broadcast -a android.intent.action.BOOT_COMPLETED -n com.android.providers.media/.MediaScannerReceiver"
Change-Id: If3c74a11ba76fa025a8dff0a7fc807e4bfa86119

services/core/java/com/android/server/am/BroadcastDispatcher.java

@@ -580,6 +580,11 @@ public class BroadcastDispatcher {
     // ----------------------------------
     // BroadcastQueue operation support
     void enqueueOrderedBroadcastLocked(BroadcastRecord r) {
+        if (r.receivers == null || r.receivers.isEmpty()) {
+            mOrderedBroadcasts.add(r);
+            return;
+        }
+
         if (Intent.ACTION_LOCKED_BOOT_COMPLETED.equals(r.intent.getAction())) {
             // Create one BroadcastRecord for each UID that can be deferred.
             final SparseArray<BroadcastRecord> deferred =

services/core/java/com/android/server/am/BroadcastRecord.java

@@ -414,6 +414,10 @@ final class BroadcastRecord extends Binder {
             return ret;
         }
 
+        if (receivers == null) {
+            return ret;
+        }
+
         final String action = intent.getAction();
         if (!Intent.ACTION_LOCKED_BOOT_COMPLETED.equals(action)
                 && !Intent.ACTION_BOOT_COMPLETED.equals(action)) {