Null checks on content resolver query

Bug: 33584356
Test: manual
Change-Id: I05dac1ead1ec1f868f8422d82f245e34a4986ccf

services/core/java/com/android/server/notification/CalendarTracker.java

@@ -180,12 +180,12 @@ public class CalendarTracker {
         final Cursor cursor = mUserContext.getContentResolver().query(Attendees.CONTENT_URI,
                 ATTENDEE_PROJECTION, selection, selectionArgs, null);
         try {
-            if (cursor.getCount() == 0) {
+            if (cursor == null || cursor.getCount() == 0) {
                 if (DEBUG) Log.d(TAG, "No attendees found");
                 return true;
             }
             boolean rt = false;
-            while (cursor.moveToNext()) {
+            while (cursor != null && cursor.moveToNext()) {
                 final long rowEventId = cursor.getLong(0);
                 final String rowEmail = cursor.getString(1);
                 final int status = cursor.getInt(2);
@@ -200,7 +200,9 @@ public class CalendarTracker {
             }
             return rt;
         } finally {
-            cursor.close();
+            if (cursor != null) {
+                cursor.close();
+            }
             if (DEBUG) Log.d(TAG, "meetsAttendee took " + (System.currentTimeMillis() - start));
         }
     }