[PaintTiming] Add form control test for FCP

This CL adds a test to ensure that FCP is not triggered when there's a textfield with no text but is triggered when there's text. Spec issue: https://github.com/w3c/paint-timing/issues/52 Bug: 1059427 Change-Id: I4cf4f961d43bfa92d6be2abd519a9d8acfde8141 Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2091968 Commit-Queue: Nicolás Peña Moreno <npm@chromium.org> Reviewed-by: Annie Sullivan <sullivan@chromium.org> Cr-Commit-Position: refs/heads/master@{#748243}

[PaintTiming] Add form control test for FCP
This CL adds a test to ensure that FCP is not triggered when there's a textfield with no text but is triggered when there's text. Spec issue: https://github.com/w3c/paint-timing/issues/52 Bug: 1059427 Change-Id: I4cf4f961d43bfa92d6be2abd519a9d8acfde8141 Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2091968 Commit-Queue: Nicolás Peña Moreno <npm@chromium.org> Reviewed-by: Annie Sullivan <sullivan@chromium.org> Cr-Commit-Position: refs/heads/master@{#748243}
425d0481 · Nicolás Peña Moreno · Commit Bot · 6700d124 · 425d0481 · 425d0481
Commit 425d0481 authored Mar 09, 2020 by Nicolás Peña Moreno Committed by Commit Bot Mar 09, 2020
2 changed files
--- a/third_party/blink/web_tests/external/wpt/paint-timing/input-text.html
+++ b/third_party/blink/web_tests/external/wpt/paint-timing/input-text.html
+<!DOCTYPE html>
+<body>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="resources/utils.js"></script>
+<form>
+  <input type="text" id='myInput'>
+</form>
+<script>
+promise_test(async () => {
+  const onload = new Promise(r => window.addEventListener('load', r));
+  await onload;
+  return assertNoFirstContentfulPaint().then(() => {
+    document.getElementById('myInput').value = 'default text';
+    return assertFirstContentfulPaint();
+  })
+});
+</script>
+</body>
--- a/third_party/blink/web_tests/external/wpt/paint-timing/resources/utils.js
+++ b/third_party/blink/web_tests/external/wpt/paint-timing/resources/utils.js
+// We use requestAnimationFrame() calls to force the user agent to paint. Hence, set
+// |numFramesWaiting| to 3 and use that constant whenever the test needs to wait for
+// the next paint to occur.
+const numFramesWaiting = 3;
+function waitForAnimationFrames(count) {
+  return new Promise(resolve => {
+    if (count-- <= 0) {
+      resolve();
+    } else {
+      requestAnimationFrame(() => {
+        waitForAnimationFrames(count).then(resolve);
+      });
+    }
+  });
+}
+function assertNoFirstContentfulPaint() {
+  return waitForAnimationFrames(numFramesWaiting).then(() => {
+    return new Promise((resolve, reject) => {
+      const observer = new PerformanceObserver(entryList =>{
+        const entries = entryList.getEntriesByName('first-contentful-paint');
+        observer.disconnect();
+        if (entries.length > 0)
+          reject('Received a first contentful paint entry.');
+        else
+          resolve();
+      });
+      observer.observe({type: 'paint', buffered: true});
+      observer.observe({type: 'mark'});
+      performance.mark('flush');
+    });
+  });
+}
+function assertFirstContentfulPaint() {
+  return waitForAnimationFrames(numFramesWaiting).then(() => {
+    return new Promise((resolve, reject) => {
+      const observer = new PerformanceObserver(entryList =>{
+        const entries = entryList.getEntriesByName('first-contentful-paint');
+        observer.disconnect();
+        if (entries.length === 0)
+          reject('Did not receive a first contentful paint entry.');
+        else {
+          resolve();
+        }
+      });
+      observer.observe({type: 'paint', buffered: true});
+      observer.observe({type: 'mark'});
+      performance.mark('flush');
+    });
+  });
+}