| Index: cc/trees/proxy_main.cc | 
| diff --git a/cc/trees/proxy_main.cc b/cc/trees/proxy_main.cc | 
| index 4c3d4a43864ebd01605cd740cf75991b4805e945..e208c9b9f6b31080199490cb165b926f101301de 100644 | 
| --- a/cc/trees/proxy_main.cc | 
| +++ b/cc/trees/proxy_main.cc | 
| @@ -184,6 +184,11 @@ void ProxyMain::BeginMainFrame( | 
|  | 
| current_pipeline_stage_ = ANIMATE_PIPELINE_STAGE; | 
|  | 
| +  if (begin_main_frame_state->begin_frame_callbacks) { | 
| +    for (auto& callback : *begin_main_frame_state->begin_frame_callbacks) | 
| +      callback.Run(); | 
| +  } | 
| + | 
| layer_tree_host_->ApplyScrollAndScale( | 
| begin_main_frame_state->scroll_info.get()); | 
|  | 
|  |