Auto merge of #19569 - asajeffrey:script-perf-measure-topLevelDomComplete, r=jdm

Add a topLevelDomComplete metric.

<!-- Please describe your changes on the following line: -->

Measure DOM completion without iframes. This is in support of measuring when the main document is loaded, ignoring secondary content, e.g. ads.

---
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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 #19561
- [X] There are tests for these changes

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components/script/document_loader.rs

@@ -141,6 +141,13 @@ impl DocumentLoader {
         !self.blocking_loads.is_empty()
     }
 
+    pub fn is_only_blocked_by_iframes(&self) -> bool {
+        self.blocking_loads.iter().all(|load| match *load {
+            LoadType::Subframe(_) => true,
+            _ => false
+        })
+    }
+
     pub fn inhibit_events(&mut self) {
         self.events_inhibited = true;
     }

components/script/dom/document.rs

@@ -322,6 +322,7 @@ pub struct Document {
     dom_content_loaded_event_start: Cell<u64>,
     dom_content_loaded_event_end: Cell<u64>,
     dom_complete: Cell<u64>,
+    top_level_dom_complete: Cell<u64>,
     load_event_start: Cell<u64>,
     load_event_end: Cell<u64>,
     /// <https://html.spec.whatwg.org/multipage/#concept-document-https-state>
@@ -1627,6 +1628,12 @@ impl Document {
         // asap_in_order_script_loaded.
 
         let loader = self.loader.borrow();
+
+        // Servo measures when the top-level content (not iframes) is loaded.
+        if (self.top_level_dom_complete.get() == 0) && loader.is_only_blocked_by_iframes() {
+            update_with_current_time_ms(&self.top_level_dom_complete);
+        }
+
         if loader.is_blocked() || loader.events_inhibited() {
             // Step 6.
             return;
@@ -1951,6 +1958,10 @@ impl Document {
         self.dom_complete.get()
     }
 
+    pub fn get_top_level_dom_complete(&self) -> u64 {
+        self.top_level_dom_complete.get()
+    }
+
     pub fn get_load_event_start(&self) -> u64 {
         self.load_event_start.get()
     }
@@ -2265,6 +2276,7 @@ impl Document {
             dom_content_loaded_event_start: Cell::new(Default::default()),
             dom_content_loaded_event_end: Cell::new(Default::default()),
             dom_complete: Cell::new(Default::default()),
+            top_level_dom_complete: Cell::new(Default::default()),
             load_event_start: Cell::new(Default::default()),
             load_event_end: Cell::new(Default::default()),
             https_state: Cell::new(HttpsState::None),

components/script/dom/performancetiming.rs

@@ -86,6 +86,12 @@ impl PerformanceTimingMethods for PerformanceTiming {
     fn LoadEventEnd(&self) -> u64 {
         self.document.get_load_event_end()
     }
+
+    // check-tidy: no specs after this line
+    // Servo-only timing for when top-level content (not iframes) is complete
+    fn TopLevelDomComplete(&self) -> u64 {
+        self.document.get_top_level_dom_complete()
+    }
 }
 
 

components/script/dom/webidls/PerformanceTiming.webidl

@@ -29,4 +29,7 @@ interface PerformanceTiming {
   readonly attribute unsigned long long domComplete;
   readonly attribute unsigned long long loadEventStart;
   readonly attribute unsigned long long loadEventEnd;
+  /* Servo-onnly attribute for measuring when the top-level document (not iframes) is complete. */
+  [Pref="dom.testperf.enabled"]
+  readonly attribute unsigned long long topLevelDomComplete;
 };

tests/wpt/mozilla/meta/MANIFEST.json

@@ -40195,6 +40195,12 @@
      {}
     ]
    ],
+   "mozilla/window_performance_topLevelDomComplete.html": [
+    [
+     "/_mozilla/mozilla/window_performance_topLevelDomComplete.html",
+     {}
+    ]
+   ],
    "mozilla/window_requestAnimationFrame.html": [
     [
      "/_mozilla/mozilla/window_requestAnimationFrame.html",
@@ -72342,6 +72348,10 @@
    "f03283e68b82d972ad21f674243070643ef89489",
    "testharness"
   ],
+  "mozilla/window_performance_topLevelDomComplete.html": [
+   "4b953e63ffa6bf4ed1bc9a2baaea457d46502b9d",
+   "testharness"
+  ],
   "mozilla/window_requestAnimationFrame.html": [
    "86310f3e4b88cce70ef92b56e4f65f034999096e",
    "testharness"

tests/wpt/mozilla/meta/mozilla/window_performance_topLevelDomComplete.html.ini

@@ -0,0 +1,3 @@
+[window_performance_topLevelDomComplete.html]
+  type: testharness
+  prefs: [dom.testperf.enabled:true]

tests/wpt/mozilla/tests/mozilla/window_performance_topLevelDomComplete.html

@@ -0,0 +1,18 @@
+<html>
+<head>
+  <title>Performance toLevelDomComplete</title>
+  <script src="/resources/testharness.js"></script>
+  <script src="/resources/testharnessreport.js"></script>
+</head>
+<body>
+<script>
+async_test(function(t) {
+  window.onload = t.step_func(function() {
+    assert_true(performance.timing.domLoading <= performance.timing.topLevelDomComplete);
+    assert_true(performance.timing.topLevelDomComplete <= performance.timing.domComplete);
+    t.done();
+  });
+}, "performance.topLevelDomComplete");
+</script>
+</body>
+</html>