Experimental fix for scroll animation update bug. [DO NOT COMMIT THIS CHANGE]

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 6965594181cb0a4dd868f89b7894ae6e36d2fdfa..baaacb65e37ed484c52b0c8d66064a61aa1e9b49 100644
--- a/cc/trees/layer_tree_host_impl.cc
+++ b/cc/trees/layer_tree_host_impl.cc
@@ -2959,9 +2959,14 @@ InputHandler::ScrollStatus LayerTreeHostImpl::ScrollAnimated(
     if (ScrollAnimationUpdateTarget(scroll_node, delta, delayed_by)) {
       scroll_status.thread = SCROLL_ON_IMPL_THREAD;
     } else {
-      scroll_status.thread = SCROLL_IGNORED;
-      scroll_status.main_thread_scrolling_reasons =
-          MainThreadScrollingReason::kNotScrollable;
+      if (ScrollAnimationCreate(scroll_node, scroll_delta, delayed_by)) {
+        scroll_animating_latched_node_id_ = scroll_node->id;
+        scroll_status.thread = SCROLL_ON_IMPL_THREAD;
+      } else {
+        scroll_status.thread = SCROLL_IGNORED;
+        scroll_status.main_thread_scrolling_reasons =
+            MainThreadScrollingReason::kNotScrollable;
+      }
     }
     return scroll_status;
   }