Import Cobalt 21.master.0.253153
diff --git a/src/third_party/web_platform_tests/intersection-observer/cross-origin-iframe.sub.html b/src/third_party/web_platform_tests/intersection-observer/cross-origin-iframe.sub.html
new file mode 100644
index 0000000..d444237
--- /dev/null
+++ b/src/third_party/web_platform_tests/intersection-observer/cross-origin-iframe.sub.html
@@ -0,0 +1,53 @@
+<!DOCTYPE html>
+<meta name="viewport" content="width=device-width,initial-scale=1">
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="./resources/intersection-observer-test-utils.js"></script>
+
+<style>
+pre, #log {
+ position: absolute;
+ top: 0;
+ left: 200px;
+}
+iframe {
+ width: 160px;
+ height: 100px;
+ overflow-y: scroll;
+}
+.spacer {
+ height: calc(100vh + 100px);
+}
+</style>
+
+<div class="spacer"></div>
+<iframe src="http://{{hosts[alt][]}}:{{ports[http][0]}}/intersection-observer/resources/cross-origin-subframe.html" sandbox="allow-scripts"></iframe>
+<div class="spacer"></div>
+
+<script>
+async_test(function(t) {
+ var iframe = document.querySelector("iframe");
+
+ function handleMessage(event) {
+ if (event.data.hasOwnProperty('scrollTo')) {
+ document.scrollingElement.scrollTop = event.data.scrollTo;
+ waitForNotification(t, function() { iframe.contentWindow.postMessage("", "*"); },
+ "document.scrollingElement.scrollTop = " + event.data.scrollTo);
+ } else if (event.data.hasOwnProperty('actual')) {
+ checkJsonEntries(event.data.actual, event.data.expected, event.data.description);
+ } else if (event.data.hasOwnProperty('DONE')) {
+ document.scrollingElement.scrollTop = 0;
+ t.done();
+ } else {
+ var description = event.data.description;
+ waitForNotification(t, function() { iframe.contentWindow.postMessage("", "*"); }, description);
+ }
+ }
+
+ window.addEventListener("message", t.step_func(handleMessage));
+
+ iframe.onload = t.step_func(function() {
+ waitForNotification(t, function() { iframe.contentWindow.postMessage("", "*") }, "setup");
+ });
+}, "Intersection observer test with no explicit root and target in a cross-origin iframe.");
+</script>
