1 files changed, 31 insertions, 0 deletions
diff --git a/testing/web-platform/tests/longtask-timing/resources/subframe-observing-longtask.html b/testing/web-platform/tests/longtask-timing/resources/subframe-observing-longtask.html
new file mode 100644
index 0000000000..125ff1e4cb
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+++ b/testing/web-platform/tests/longtask-timing/resources/subframe-observing-longtask.html
@@ -0,0 +1,31 @@
+<!DOCTYPE HTML>
+<meta charset=utf-8>
+<meta name="viewport" content="width=device-width">
+<title>Child Iframe</title>
+<h1>Child Iframe observing long tasks</h1>
+
+<script>
+    const observer = new PerformanceObserver(function(entryList) {
+      for (i = 0; i < entryList.getEntries().length; i++) {
+        const longtask = entryList.getEntries()[i];
+         // Ignore long task generated within here, as part of making this iframe.
+         // Ignore multiple-contexts and unknown because they cause longtask-in-parentiframe test to be flaky.
+        if (longtask.name == 'self' ||
+            longtask.name == 'multiple-contexts' || longtask.name == 'unknown')
+          return;
+        // TODO(panicker): include containerType.
+        const attribution = longtask.attribution[0];
+        const entryContents = {
+          'entryType': longtask.entryType,
+          'frame-attribution': longtask.name,
+          'task-attribution': attribution.name,
+          'containerType': attribution.containerType,
+          'containerId': attribution.containerId,
+          'containerName': attribution.containerName,
+          'containerSrc': attribution.containerSrc
+        };
+        top.postMessage(entryContents, '*');
+      }
+    });
+    observer.observe({entryTypes: ['longtask']});
+</script>