Animated scroll shouldn't consume unhandled scrolls for OOPIFs.

cc/trees/layer_tree_host_impl.cc

Index: cc/trees/layer_tree_host_impl.cc
diff --git a/cc/trees/layer_tree_host_impl.cc b/cc/trees/layer_tree_host_impl.cc
index ca08b6f24da33a3b3a56811fee6ffd2e2cf9bc5a..67483420502ad7c9b19fab1b834352690fb269a3 100644
--- a/cc/trees/layer_tree_host_impl.cc
+++ b/cc/trees/layer_tree_host_impl.cc
@@ -3035,6 +3035,14 @@ InputHandler::ScrollStatus LayerTreeHostImpl::ScrollAnimated(
   }
   scroll_state.set_is_ending(true);
   ScrollEnd(&scroll_state);
+  if (settings_.is_layer_tree_for_subframe &&
+      scroll_status.thread == SCROLL_ON_IMPL_THREAD) {
+    // If we get to here, we shouldn't return SCROLL_ON_IMPL_THREAD as otherwise
+    // we'll mark the scroll as handled and the scroll won't bubble.
+    scroll_status.thread = SCROLL_IGNORED;
+    scroll_status.main_thread_scrolling_reasons =
+        MainThreadScrollingReason::kNotScrollable;
+  }
   return scroll_status;
 }