From 31096e1a0f225e94a1aed865a1ab182bf27f873f Mon Sep 17 00:00:00 2001
From: Martin Robinson <mrobinson@igalia.com>
Date: Thu, 31 Jul 2025 10:13:41 +0200
Subject: [PATCH] Send idle messages as part of messaging loop

---
 components/script/dom/document.rs  |  7 +------
 components/script/dom/window.rs    |  4 ++++
 components/script/script_thread.rs | 13 +++++++++++++
 3 files changed, 18 insertions(+), 6 deletions(-)

diff --git a/components/script/dom/document.rs b/components/script/dom/document.rs
index 11a6a4d0a12..ea57e7a3b41 100644
--- a/components/script/dom/document.rs
+++ b/components/script/dom/document.rs
@@ -3723,12 +3723,7 @@ impl Document {
             receiver.recv().unwrap();
         }
 
-        let result = self.window().reflow(ReflowGoal::UpdateTheRendering, can_gc);
-
-        self.window()
-            .maybe_send_idle_document_state_to_constellation();
-
-        result
+        self.window().reflow(ReflowGoal::UpdateTheRendering, can_gc)
     }
 
     pub(crate) fn id_map(&self) -> Ref<HashMapTracedValues<Atom, Vec<Dom<Element>>>> {
diff --git a/components/script/dom/window.rs b/components/script/dom/window.rs
index f4330ccecb7..e3cc0b2a7cb 100644
--- a/components/script/dom/window.rs
+++ b/components/script/dom/window.rs
@@ -2345,6 +2345,10 @@ impl Window {
             return;
         }
 
+        if self.Document().needs_rendering_update() {
+            return;
+        }
+
         // When all these conditions are met, notify the constellation
         // that this pipeline is ready to write the image (from the script thread
         // perspective at least).
diff --git a/components/script/script_thread.rs b/components/script/script_thread.rs
index e8222290d0a..6f9ae280976 100644
--- a/components/script/script_thread.rs
+++ b/components/script/script_thread.rs
@@ -1437,6 +1437,18 @@ impl ScriptThread {
         );
     }
 
+    fn maybe_send_idle_document_state_to_constellation(&self) {
+        if !opts::get().wait_for_stable_image {
+            return;
+        }
+
+        for (_, document) in self.documents.borrow().iter() {
+            document
+                .window()
+                .maybe_send_idle_document_state_to_constellation();
+        }
+    }
+
     /// Handle incoming messages from other tasks and the task queue.
     fn handle_msgs(&self, can_gc: CanGc) -> bool {
         // Proritize rendering tasks and others, and gather all other events as `sequential`.
@@ -1647,6 +1659,7 @@ impl ScriptThread {
         }
 
         self.maybe_schedule_rendering_opportunity_after_ipc_message(can_gc);
+        self.maybe_send_idle_document_state_to_constellation();
 
         true
     }