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diff --git a/testing/web-platform/tests/element-timing/background-image-stretched.html b/testing/web-platform/tests/element-timing/background-image-stretched.html
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+++ b/testing/web-platform/tests/element-timing/background-image-stretched.html
@@ -0,0 +1,39 @@
+<!DOCTYPE HTML>
+<meta charset=utf-8>
+<title>Element Timing: observe larger element with stretched background image</title>
+<body>
+<style>
+body {
+  margin: 0;
+}
+#target {
+  width: 200px;
+  height: 150px;
+  background-image: url('resources/square100.png');
+}
+</style>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="resources/element-timing-helpers.js"></script>
+<script>
+  let beforeRender = performance.now();
+  async_test(function (t) {
+    assert_implements(window.PerformanceElementTiming, "PerformanceElementTiming is not implemented");
+    const observer = new PerformanceObserver(
+      t.step_func_done(function(entryList) {
+        assert_equals(entryList.getEntries().length, 1);
+        const entry = entryList.getEntries()[0];
+        const pathname = window.location.origin + '/element-timing/resources/square100.png';
+        checkElement(entry, pathname, 'my_div', 'target', beforeRender,
+            document.getElementById('target'));
+        // The background image extends to occupy to full size of the div.
+        checkRect(entry, [0, 200, 0, 150]);
+        // The natural size of the square remains unchanged.
+        checkNaturalSize(entry, 100, 100);
+      })
+    );
+    observer.observe({entryTypes: ['element']});
+  }, 'Element with background image shows correct image size.');
+</script>
+<div id='target' elementtiming='my_div'></div>
+</body>