1 files changed, 25 insertions, 0 deletions
diff --git a/testing/web-platform/tests/resource-timing/resources/observe-entry.js b/testing/web-platform/tests/resource-timing/resources/observe-entry.js
new file mode 100644
index 0000000000..260b5929a5
--- /dev/null
+++ b/testing/web-platform/tests/resource-timing/resources/observe-entry.js
@@ -0,0 +1,25 @@
+// Given a resource name, returns a promise that will resolve to the
+// corresponding PerformanceResourceTiming entry. The promise will reject,
+// however, if the PerformanceResourceTiming entry isn't observed within ~2
+// seconds (scaled according to WPT timeout scaling).
+const observe_entry = entry_name => {
+  const entry = new Promise(resolve => {
+    new PerformanceObserver((entry_list, observer) => {
+      for (const entry of entry_list.getEntries()) {
+        if (entry.name.endsWith(entry_name)) {
+          resolve(entry);
+          observer.disconnect();
+          return;
+        }
+      }
+    }).observe({"type": "resource", "buffered": true});
+  });
+  const timeout = new Promise((resolve, reject) => {
+    step_timeout(() => {
+      reject(new Error("observe_entry: timeout"));
+    }, 2000);
+  });
+  // If the entry isn't observed within 2 seconds, assume it will never show
+  // up.
+  return Promise.race([entry, timeout]);
+};