Fix UB with LayerTreeImpl::PassSwapPromises usage

cc/trees/layer_tree_impl.cc

Index: cc/trees/layer_tree_impl.cc
diff --git a/cc/trees/layer_tree_impl.cc b/cc/trees/layer_tree_impl.cc
index 0f0a4da885297f60b68da03d91be19dcaf6303dd..fdd79d7a9659e1264154694d7f2c91e372f6cbef 100644
--- a/cc/trees/layer_tree_impl.cc
+++ b/cc/trees/layer_tree_impl.cc
@@ -426,6 +426,7 @@ void LayerTreeImpl::PushPropertiesTo(LayerTreeImpl* target_tree) {
   }
 
   target_tree->PassSwapPromises(std::move(swap_promise_list_));
+  swap_promise_list_.clear();
 
   target_tree->set_top_controls_shrink_blink_size(
       top_controls_shrink_blink_size_);