Reland "[EventTiming] Round instead of ceil the |duration|"

This is a reland of 9ac1e68e

Original change's description:
> [EventTiming] Round instead of ceil the |duration|
> 
> The purpose of this change is to expose entries whose |duration| is >=
> 100ms.
> 
> Bug: 823744
> Change-Id: Ibb089009ba287769b1365a938cc7564278a86c35
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1594818
> Reviewed-by: Timothy Dresser <tdresser@chromium.org>
> Commit-Queue: Nicolás Peña Moreno <npm@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#656797}

Bug: 823744
Change-Id: Ia7ceffaf7dc84951b74fff507b024a3f895039db
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1596849Reviewed-by: Timothy Dresser <tdresser@chromium.org>
Commit-Queue: Nicolás Peña Moreno <npm@chromium.org>
Cr-Commit-Position: refs/heads/master@{#656927}

third_party/blink/renderer/core/timing/window_performance.cc

@@ -365,7 +365,7 @@ void WindowPerformance::ReportEventTimings(WebWidgetClient::SwapResult result,
 
   DOMHighResTimeStamp end_time = MonotonicTimeToDOMHighResTimeStamp(timestamp);
   for (const auto& entry : event_timings_) {
-    int duration_in_ms = std::ceil((end_time - entry->startTime()) / 8) * 8;
+    int duration_in_ms = std::round((end_time - entry->startTime()) / 8) * 8;
     entry->SetDuration(duration_in_ms);
     if (!first_input_timing_) {
       if (entry->name() == "pointerdown") {

third_party/blink/renderer/core/timing/window_performance_test.cc

@@ -252,6 +252,28 @@ TEST_F(WindowPerformanceTest, EventTimingBeforeOnLoad) {
   performance_->clearEventTimings();
 }
 
+TEST_F(WindowPerformanceTest, Expose100MsEvents) {
+  ScopedEventTimingForTest event_timing(true);
+  TimeTicks start_time = GetTimeOrigin() + TimeDelta::FromSeconds(1);
+  TimeTicks processing_start = start_time + TimeDelta::FromMilliseconds(10);
+  TimeTicks processing_end = processing_start + TimeDelta::FromMilliseconds(10);
+  performance_->RegisterEventTiming("mousedown", start_time, processing_start,
+                                    processing_end, false);
+
+  TimeTicks start_time2 = start_time + TimeDelta::FromMicroseconds(200);
+  performance_->RegisterEventTiming("click", start_time2, processing_start,
+                                    processing_end, false);
+
+  // The swap time is 100.1 ms after |start_time| but only 99.9 ms after
+  // |start_time2|.
+  TimeTicks swap_time = start_time + TimeDelta::FromMicroseconds(100100);
+  SimulateSwapPromise(swap_time);
+  // Only the longer event should have been reported.
+  EXPECT_EQ(1u, performance_->getEntriesByType("event").size());
+  EXPECT_EQ(1u, performance_->getEntriesByName("mousedown", "event").size());
+  EXPECT_EQ(0u, performance_->getEntriesByName("click", "event").size());
+}
+
 TEST_F(WindowPerformanceTest, EventTimingDuration) {
   ScopedEventTimingForTest event_timing(true);
 
@@ -270,7 +292,7 @@ TEST_F(WindowPerformanceTest, EventTimingDuration) {
   performance_->RegisterEventTiming("click", start_time, processing_start,
                                     processing_end, true);
   TimeTicks long_swap_time =
-      GetTimeOrigin() + TimeDelta::FromMilliseconds(1100);
+      GetTimeOrigin() + TimeDelta::FromMilliseconds(2000);
   SimulateSwapPromise(long_swap_time);
   EXPECT_EQ(1u, performance_->getEntriesByName("click", "event").size());
 

third_party/blink/web_tests/external/wpt/event-timing/event-timing-retrieve-firstInput.html

@@ -23,7 +23,7 @@
       const entry = performance.getEntriesByType('firstInput')[0];
       assert_equals(entry.name, 'mousedown');
       assert_equals(entry.entryType, 'firstInput');
-      assert_greater_than(entry.duration, 50,
+      assert_greater_than_equal(entry.duration, 104,
         "The first input was a long one.");
       t.done();
     }

third_party/blink/web_tests/external/wpt/event-timing/resources/event-timing-support.js

@@ -35,7 +35,9 @@ function verifyClickEvent(entry, is_first=false) {
       "The entry's processingStart should be greater than startTime.");
   assert_greater_than_equal(entry.processingEnd, entry.processingStart,
       "The entry's processingEnd must be at least as large as processingStart.");
-  assert_greater_than_equal(entry.duration, entry.processingEnd - entry.startTime,
+  // |duration| is a number rounded to the nearest 8 ms, so add 4 to get a lower bound
+  // on the actual duration.
+  assert_greater_than_equal(entry.duration + 4, entry.processingEnd - entry.startTime,
       "The entry's duration must be at least as large as processingEnd - startTime.");
   if (is_first) {
     let firstInputs = performance.getEntriesByType('firstInput');