layout: Add instrumentation for display_list (#34128)

* Add instrumentation for display_list

Signed-off-by: atbrakhi <atbrakhi@igalia.com>

* review update

Signed-off-by: atbrakhi <atbrakhi@igalia.com>

* review fix

Signed-off-by: atbrakhi <atbrakhi@igalia.com>

---------

Signed-off-by: atbrakhi <atbrakhi@igalia.com>

components/layout_2020/display_list/clip_path.rs

@@ -65,6 +65,14 @@ pub(super) fn build_clip_path_clip_chain_if_necessary(
     }
 }
 
+#[cfg_attr(
+    feature = "tracing",
+    tracing::instrument(
+        name = "display_list::build_simple_shape",
+        skip_all,
+        fields(servo_profiling = true)
+    )
+)]
 fn build_simple_shape(
     shape: BasicShape,
     layout_box: LayoutRect,

components/layout_2020/display_list/mod.rs

@@ -181,6 +181,10 @@ impl DisplayList {
         fragment_tree: &FragmentTree,
         root_stacking_context: &StackingContext,
     ) -> (FnvHashMap<BrowsingContextId, Size2D<f32, CSSPixel>>, bool) {
+        #[cfg(feature = "tracing")]
+        let span = tracing::span!(tracing::Level::TRACE, "display_list::build");
+        #[cfg(feature = "tracing")]
+        let _enter = span.enter();
         let mut builder = DisplayListBuilder {
             current_scroll_node_id: self.compositor_info.root_reference_frame_id,
             current_reference_frame_scroll_node_id: self.compositor_info.root_reference_frame_id,

components/layout_2020/display_list/stacking_context.rs

@@ -101,6 +101,14 @@ impl DisplayList {
         SpatialTreeItemKey::new(pipeline_tag, self.spatial_tree_count)
     }
 
+    #[cfg_attr(
+        feature = "tracing",
+        tracing::instrument(
+            name = "display_list::build_stacking_context_tree",
+            skip_all,
+            fields(servo_profiling = true)
+        )
+    )]
     pub fn build_stacking_context_tree(
         &mut self,
         fragment_tree: &FragmentTree,