Fix ANR when leaving MediaPreviewActivity.

app/src/main/java/org/thoughtcrime/securesms/util/LifecycleCursorWrapper.java

@@ -8,6 +8,8 @@ import androidx.lifecycle.DefaultLifecycleObserver;
 import androidx.lifecycle.Lifecycle;
 import androidx.lifecycle.LifecycleOwner;
 
+import org.signal.core.util.concurrent.SignalExecutors;
+
 /**
  * Wraps a {@link Cursor} that will be closed automatically when the {@link Lifecycle.Event}.ON_DESTROY
  * is fired from the lifecycle this object is observing.
@@ -22,4 +24,9 @@ public class LifecycleCursorWrapper extends CursorWrapper implements DefaultLife
   public void onDestroy(@NonNull LifecycleOwner owner) {
     close();
   }
+
+  @Override
+  public void close() {
+    SignalExecutors.BOUNDED.execute(super::close);
+  }
 }