Auto merge of #23115 - pylbrecht:measure.blocked.layout.queries, r=jdm

measure blocked layout queries

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- [X] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [x] These changes fix #19797

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- [ ] There are tests for these changes

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components/constellation/pipeline.rs

@@ -40,6 +40,7 @@ use std::env;
 use std::ffi::OsStr;
 use std::process;
 use std::rc::Rc;
+use std::sync::atomic::AtomicBool;
 use std::sync::Arc;
 use style_traits::CSSPixel;
 use style_traits::DevicePixel;
@@ -528,6 +529,7 @@ impl UnprivilegedPipelineContent {
             self.script_chan.clone(),
             self.load_data.url.clone(),
         );
+        let layout_thread_busy_flag = Arc::new(AtomicBool::new(false));
         let layout_pair = STF::create(
             InitialScriptState {
                 id: self.id,
@@ -554,6 +556,7 @@ impl UnprivilegedPipelineContent {
                 webvr_chan: self.webvr_chan,
                 webrender_document: self.webrender_document,
                 webrender_api_sender: self.webrender_api_sender.clone(),
+                layout_is_busy: layout_thread_busy_flag.clone(),
             },
             self.load_data.clone(),
         );
@@ -576,6 +579,7 @@ impl UnprivilegedPipelineContent {
             self.webrender_api_sender,
             self.webrender_document,
             paint_time_metrics,
+            layout_thread_busy_flag.clone(),
         );
 
         if wait_for_completion {