Deflake inspector-protocol/performance-timeline/largest-contentful-paint.js

Bug: 1164469
Change-Id: I0fab507f0a58676abd0143e5bb8ea562bfb113f4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2628083
Commit-Queue: Peter Kvitek <kvitekp@chromium.org>
Reviewed-by: Peter Kvitek <kvitekp@chromium.org>
Cr-Commit-Position: refs/heads/master@{#844196}

third_party/blink/web_tests/TestExpectations

@@ -71,7 +71,6 @@ crbug.com/1132260 http/tests/devtools/console/console-bad-stacktrace.js [ Pass F
 crbug.com/1132260 http/tests/devtools/console/console-uncaught-promise.js [ Pass Failure ]
 crbug.com/1132260 http/tests/devtools/tracing/timeline-network/timeline-network-resource-details.js [ Pass Failure ]
 crbug.com/1132260 inspector-protocol/page/frameAttachedStacktrace.js [ Pass Failure ]
-crbug.com/1164469 inspector-protocol/performance-timeline/largest-contentful-paint.js [ Pass Failure ]
 
 # With --enable-display-compositor-pixel-dump enabled by default, these three
 # tests fail. See crbug.com/887140 for more info.

third_party/blink/web_tests/inspector-protocol/performance-timeline/largest-contentful-paint.js

@@ -3,12 +3,12 @@
   const unstableFields = ['frameId'];
 
   const events = [];
-  const startTime = Date.now();
-  await dp.PerformanceTimeline.enable({eventTypes: ['largest-contentful-paint']});
 
   const TestHelper = await testRunner.loadScript('resources/performance-timeline-test.js');
   const testHelper = new TestHelper(dp);
 
+  await dp.PerformanceTimeline.enable({eventTypes: ['largest-contentful-paint']});
+
   dp.PerformanceTimeline.onTimelineEventAdded(event => events.push(event.params.event));
   session.navigate(testRunner.url('resources/lcp.html'));
   await dp.PerformanceTimeline.onceTimelineEventAdded();
@@ -24,8 +24,8 @@
   const endTime = Date.now();
 
   for (const event of events) {
-    testHelper.patchTimes(startTime, endTime, event, ['time']);
-    testHelper.patchTimes(startTime, endTime, event.lcpDetails, ['renderTime', 'loadTime']);
+    testHelper.patchTimes(event, ['time']);
+    testHelper.patchTimes(event.lcpDetails, ['renderTime', 'loadTime']);
     await patchFields(event.lcpDetails);
   }
 

third_party/blink/web_tests/inspector-protocol/performance-timeline/layout-shift.js

@@ -3,13 +3,12 @@
   const unstableFields = ['frameId'];
 
   const events = [];
-  const startTime = Date.now();
-
-  await dp.PerformanceTimeline.enable({eventTypes: ['layout-shift']});
 
   const TestHelper = await testRunner.loadScript('resources/performance-timeline-test.js');
   const testHelper = new TestHelper(dp);
 
+  await dp.PerformanceTimeline.enable({eventTypes: ['layout-shift']});
+
   dp.PerformanceTimeline.onTimelineEventAdded(event => events.push(event.params.event));
   await session.navigate(testRunner.url('resources/layout-shift.html'));
   await session.evaluateAsync(`new Promise(resolve => requestAnimationFrame(resolve))`);
@@ -25,11 +24,9 @@
 
   await dp.PerformanceTimeline.onceTimelineEventAdded();
 
-  const endTime = Date.now();
-
   for (const event of events) {
-    testHelper.patchTimes(startTime, endTime, event, ['time']);
-    testHelper.patchTimes(startTime, endTime, event.layoutShiftDetails, ['lastInputTime']);
+    testHelper.patchTimes(event, ['time']);
+    testHelper.patchTimes(event.layoutShiftDetails, ['lastInputTime']);
     await patchFields(event.layoutShiftDetails);
   }
 

third_party/blink/web_tests/inspector-protocol/performance-timeline/resources/performance-timeline-test.js

@@ -7,6 +7,7 @@
 class TestHelper {
   constructor(dp) {
     this._dp = dp;
+    this._startTicks = performance.now();
   }
 
   async describeNode(nodeId) {
@@ -15,16 +16,19 @@ class TestHelper {
         `<${response.result.object.description}>` : '<invalid id>';
   }
 
-  patchTimes(start, end, obj, fields) {
-    // Add some slack to defeat time clamping.
-    start -= 1;
-    end += 1;
+  async patchTimes(obj, fields) {
+    const startTime = (await this._dp.Runtime.evaluate({
+        expression: 'window.performance.timeOrigin',
+        returnByValue: true})).result.result.value;
+    const endTicks = performance.now();
+    // Ensure we're using monotonic time within the test duration.
+    const endTime = startTime + (endTicks - this._startTicks);
     for (const field of fields) {
       const time = obj[field] * 1000;
-      if (time && (start <= time && time <= end)) {
+      if (time && (startTime <= time && time <= endTime)) {
         obj[field] = `<${typeof time}>`;
       } else if (time) {
-        obj[field] = `FAIL: actual: ${time}, expected: ${start} <= time <= ${end}`
+        obj[field] = `FAIL: actual: ${time}, expected: ${startTime} <= time <= ${endTime}`;
       }
     }
   }