| // Copyright 2019 The Chromium Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #include "ui/latency/average_lag_tracker.h" |
| |
| #include "base/test/metrics/histogram_tester.h" |
| #include "testing/gmock/include/gmock/gmock.h" |
| #include "testing/gtest/include/gtest/gtest.h" |
| |
| using base::Bucket; |
| using testing::ElementsAre; |
| |
| namespace ui { |
| namespace { |
| |
| class AverageLagTrackerTest : public testing::Test { |
| public: |
| AverageLagTrackerTest() { ResetHistograms(); } |
| |
| void ResetHistograms() { |
| histogram_tester_.reset(new base::HistogramTester()); |
| } |
| |
| const base::HistogramTester& histogram_tester() { return *histogram_tester_; } |
| |
| void SetUp() override { |
| average_lag_tracker_ = std::make_unique<AverageLagTracker>(); |
| } |
| |
| void SyntheticTouchScrollBeginLatencyInfo(base::TimeTicks event_time, |
| base::TimeTicks frame_time, |
| float delta, |
| float predicted_delta = 0) { |
| ui::LatencyInfo touch_latency(ui::SourceEventType::TOUCH); |
| touch_latency.set_scroll_update_delta(delta); |
| touch_latency.set_predicted_scroll_update_delta( |
| predicted_delta != 0 ? predicted_delta : delta); |
| |
| touch_latency.AddLatencyNumberWithTimestamp( |
| ui::INPUT_EVENT_LATENCY_FIRST_SCROLL_UPDATE_ORIGINAL_COMPONENT, |
| event_time, 1); |
| touch_latency.AddLatencyNumberWithTimestamp( |
| ui::INPUT_EVENT_LATENCY_SCROLL_UPDATE_LAST_EVENT_COMPONENT, event_time, |
| 1); |
| average_lag_tracker_->AddLatencyInFrame(touch_latency, frame_time, |
| "ScrollBegin"); |
| } |
| |
| void SyntheticTouchScrollUpdateLatencyInfo(base::TimeTicks event_time, |
| base::TimeTicks frame_time, |
| float delta, |
| float predicted_delta = 0) { |
| ui::LatencyInfo touch_latency(ui::SourceEventType::TOUCH); |
| touch_latency.set_scroll_update_delta(delta); |
| touch_latency.set_predicted_scroll_update_delta( |
| predicted_delta != 0 ? predicted_delta : delta); |
| touch_latency.AddLatencyNumberWithTimestamp( |
| ui::INPUT_EVENT_LATENCY_SCROLL_UPDATE_ORIGINAL_COMPONENT, event_time, |
| 1); |
| touch_latency.AddLatencyNumberWithTimestamp( |
| ui::INPUT_EVENT_LATENCY_SCROLL_UPDATE_LAST_EVENT_COMPONENT, event_time, |
| 1); |
| average_lag_tracker_->AddLatencyInFrame(touch_latency, frame_time, |
| "ScrollUpdate"); |
| } |
| |
| protected: |
| std::unique_ptr<AverageLagTracker> average_lag_tracker_; |
| |
| std::unique_ptr<base::HistogramTester> histogram_tester_; |
| }; |
| |
| base::TimeTicks MillisecondsToTimeTicks(float t_ms) { |
| return base::TimeTicks() + base::TimeDelta::FromMilliseconds(t_ms); |
| } |
| |
| // Simulate a simple situation that events at every 10ms and start at t=15ms, |
| // frame swaps at every 10ms too and start at t=20ms and test we record one |
| // UMA for ScrollUpdate in one second. |
| TEST_F(AverageLagTrackerTest, OneSecondInterval) { |
| base::TimeTicks event_time = |
| base::TimeTicks() + base::TimeDelta::FromMilliseconds(5); |
| base::TimeTicks frame_time = |
| base::TimeTicks() + base::TimeDelta::FromMilliseconds(10); |
| float scroll_delta = 10; |
| |
| // ScrollBegin |
| event_time += base::TimeDelta::FromMilliseconds(10); // 15ms |
| frame_time += base::TimeDelta::FromMilliseconds(10); // 20ms |
| SyntheticTouchScrollBeginLatencyInfo(event_time, frame_time, scroll_delta); |
| |
| // Send 101 ScrollUpdate events to verify that there is 1 AverageLag record |
| // per 1 second. |
| const int kUpdates = 101; |
| for (int i = 0; i < kUpdates; i++) { |
| event_time += base::TimeDelta::FromMilliseconds(10); |
| frame_time += base::TimeDelta::FromMilliseconds(10); |
| // First 50 has positive delta, others negetive delta. |
| const int sign = (i < kUpdates / 2) ? 1 : -1; |
| SyntheticTouchScrollUpdateLatencyInfo(event_time, frame_time, |
| sign * scroll_delta); |
| } |
| |
| // ScrollBegin report_time is at 20ms, so the next ScrollUpdate report_time is |
| // at 1020ms. The last event_time that finish this report should be later than |
| // 1020ms. |
| EXPECT_EQ(event_time, |
| base::TimeTicks() + base::TimeDelta::FromMilliseconds(1025)); |
| EXPECT_EQ(frame_time, |
| base::TimeTicks() + base::TimeDelta::FromMilliseconds(1030)); |
| |
| // ScrollBegin AverageLag are the area between the event original component |
| // (time=15ms, delta=10px) to the frame swap time (time=20ms, expect finger |
| // position at delta=15px). The AverageLag scaled to 1 second is |
| // (0.5*(10px+15px)*5ms)/5ms = 12.5px. |
| EXPECT_THAT(histogram_tester().GetAllSamples( |
| "Event.Latency.ScrollBegin.Touch.AverageLag"), |
| ElementsAre(Bucket(12, 1))); |
| // This ScrollUpdate AverageLag are calculated as the finger uniformly scroll |
| // 10px each frame. For scroll up/down frame, the Lag at the last frame swap |
| // is 5px, and Lag at this frame swap is 15px. For the one changing direction, |
| // the Lag is from 5 to 10 and down to 5 again. So total LagArea is 99 * 100, |
| // plus 75. the AverageLag in 1 second is 9.975px. |
| EXPECT_THAT(histogram_tester().GetAllSamples( |
| "Event.Latency.ScrollUpdate.Touch.AverageLag"), |
| ElementsAre(Bucket(9, 1))); |
| EXPECT_THAT( |
| histogram_tester().GetAllSamples( |
| "Event.Latency.ScrollUpdate.Touch.AverageLag.PredictionPositive"), |
| ElementsAre(Bucket(0, 1))); |
| histogram_tester().ExpectTotalCount( |
| "Event.Latency.ScrollUpdate.Touch.AverageLag.PredictionNegative", 0); |
| ResetHistograms(); |
| |
| // Send another ScrollBegin to end the unfinished ScrollUpdate report. |
| event_time += base::TimeDelta::FromMilliseconds(10); |
| frame_time += base::TimeDelta::FromMilliseconds(10); |
| SyntheticTouchScrollBeginLatencyInfo(event_time, frame_time, scroll_delta); |
| |
| // The last ScrollUpdate's lag is 8.75px and truncated to 8. |
| EXPECT_THAT(histogram_tester().GetAllSamples( |
| "Event.Latency.ScrollUpdate.Touch.AverageLag"), |
| ElementsAre(Bucket(8, 1))); |
| EXPECT_THAT( |
| histogram_tester().GetAllSamples( |
| "Event.Latency.ScrollUpdate.Touch.AverageLag.PredictionPositive"), |
| ElementsAre(Bucket(0, 1))); |
| histogram_tester().ExpectTotalCount( |
| "Event.Latency.ScrollUpdate.Touch.AverageLag.PredictionNegative", 0); |
| } |
| |
| // Test the case that event's frame swap time is later than next event's |
| // creation time. (i.e, event at t=10ms will be dispatch at t=30ms, while next |
| // event is at t=20ms). |
| TEST_F(AverageLagTrackerTest, LargerLatency) { |
| base::TimeTicks event_time = MillisecondsToTimeTicks(10); |
| base::TimeTicks frame_time = |
| event_time + base::TimeDelta::FromMilliseconds(20); |
| float scroll_delta = 10; |
| |
| SyntheticTouchScrollBeginLatencyInfo(event_time, frame_time, scroll_delta); |
| |
| // Send 2 ScrollUpdate. The second one will record AverageLag.ScrollBegin as |
| // it's event_time is larger or equal to ScrollBegin's frame_time. |
| for (int i = 0; i < 2; i++) { |
| event_time += base::TimeDelta::FromMilliseconds(10); |
| frame_time = event_time + base::TimeDelta::FromMilliseconds(20); |
| SyntheticTouchScrollUpdateLatencyInfo(event_time, frame_time, scroll_delta); |
| } |
| |
| // ScrollBegin AveragLag are from t=10ms to t=30ms, with absolute scroll |
| // position from 10 to 30. The AverageLag should be: |
| // (0.5*(10px + 30px)*20ms/20ms) = 20px. |
| EXPECT_THAT(histogram_tester().GetAllSamples( |
| "Event.Latency.ScrollBegin.Touch.AverageLag"), |
| ElementsAre(Bucket(20, 1))); |
| |
| // Another ScrollBegin to flush unfinished frames. |
| // event_time doesn't matter here because the previous frames' lag are |
| // compute from their frame_time. |
| event_time = MillisecondsToTimeTicks(1000); |
| frame_time = MillisecondsToTimeTicks(1000); |
| SyntheticTouchScrollBeginLatencyInfo(event_time, frame_time, scroll_delta); |
| // The to unfinished frames' lag are (finger_positon-rendered_position)*time, |
| // AverageLag is ((30px-10px)*10ms+(30px-20px)*10ms)/20ms = 15px. |
| EXPECT_THAT(histogram_tester().GetAllSamples( |
| "Event.Latency.ScrollUpdate.Touch.AverageLag"), |
| ElementsAre(Bucket(14, 1))); |
| } |
| |
| // Test that multiple latency being flush in the same frame swap. |
| TEST_F(AverageLagTrackerTest, TwoLatencyInfoInSameFrame) { |
| // ScrollBegin |
| base::TimeTicks event_time = MillisecondsToTimeTicks(10); |
| base::TimeTicks frame_time = MillisecondsToTimeTicks(20); |
| SyntheticTouchScrollBeginLatencyInfo(event_time, frame_time, |
| -10 /* scroll_delta */); |
| |
| // ScrollUpdate with event_time >= ScrollBegin frame_time will generate |
| // a histogram for AverageLag.ScrollBegin. |
| event_time = MillisecondsToTimeTicks(20); |
| frame_time = MillisecondsToTimeTicks(30); |
| SyntheticTouchScrollUpdateLatencyInfo(event_time, frame_time, |
| -10 /* scroll_delta */); |
| |
| // Absolute position from -10 to -20. The AverageLag should be: |
| // (0.5*(10px + 20px)*10ms/10ms) = 15px. |
| EXPECT_THAT(histogram_tester().GetAllSamples( |
| "Event.Latency.ScrollBegin.Touch.AverageLag"), |
| ElementsAre(Bucket(14, 1))); |
| |
| event_time = MillisecondsToTimeTicks(25); |
| frame_time = MillisecondsToTimeTicks(30); |
| SyntheticTouchScrollUpdateLatencyInfo(event_time, frame_time, |
| 5 /* scroll_delta */); |
| |
| // Another ScrollBegin to flush unfinished frames. |
| event_time = MillisecondsToTimeTicks(1000); |
| frame_time = MillisecondsToTimeTicks(1000); |
| SyntheticTouchScrollBeginLatencyInfo(event_time, frame_time, 0); |
| |
| // The ScrollUpdates are at t=20ms, finger_pos=-20px, rendered_pos=-10px, |
| // at t=25ms, finger_pos=-15px, rendered_pos=-10px; |
| // To t=30ms both events get flush. |
| // AverageLag is (0.5*(10px+5px)*5ms + 5px*5ms)/10ms = 6.25px |
| EXPECT_THAT(histogram_tester().GetAllSamples( |
| "Event.Latency.ScrollUpdate.Touch.AverageLag"), |
| ElementsAre(Bucket(6, 1))); |
| } |
| |
| // Test the case that switching direction causes lag at current frame |
| // time and previous frame time are in different direction. |
| TEST_F(AverageLagTrackerTest, ChangeDirectionInFrame) { |
| // ScrollBegin |
| base::TimeTicks event_time = MillisecondsToTimeTicks(10); |
| base::TimeTicks frame_time = MillisecondsToTimeTicks(20); |
| SyntheticTouchScrollBeginLatencyInfo(event_time, frame_time, |
| 10 /* scroll_delta */); |
| |
| // At t=20, lag = 10px. |
| event_time = MillisecondsToTimeTicks(20); |
| frame_time = MillisecondsToTimeTicks(30); |
| SyntheticTouchScrollUpdateLatencyInfo(event_time, frame_time, |
| 10 /* scroll_delta */); |
| |
| // At t=30, lag = -10px. |
| event_time = MillisecondsToTimeTicks(30); |
| frame_time = MillisecondsToTimeTicks(40); |
| SyntheticTouchScrollUpdateLatencyInfo(event_time, frame_time, |
| -20 /* scroll_delta */); |
| |
| // Another ScrollBegin to flush unfinished frames. |
| event_time = MillisecondsToTimeTicks(1000); |
| frame_time = MillisecondsToTimeTicks(1000); |
| SyntheticTouchScrollBeginLatencyInfo(event_time, frame_time, 0); |
| |
| // From t=20 to t=30, lag_area=2*(0.5*10px*5ms)=50px*ms. |
| // From t=30 to t=40, lag_area=20px*10ms=200px*ms |
| // AverageLag = (50+200)/20 = 12.5px. |
| EXPECT_THAT(histogram_tester().GetAllSamples( |
| "Event.Latency.ScrollUpdate.Touch.AverageLag"), |
| ElementsAre(Bucket(12, 1))); |
| } |
| |
| // A simple case without scroll prediction to compare with the two with |
| // prediction cases below. |
| TEST_F(AverageLagTrackerTest, NoScrollPrediction) { |
| // ScrollBegin, at t=5, finger_pos=5px. |
| base::TimeTicks event_time = MillisecondsToTimeTicks(5); |
| base::TimeTicks frame_time = MillisecondsToTimeTicks(10); |
| SyntheticTouchScrollBeginLatencyInfo(event_time, frame_time, |
| 5 /* scroll_delta */); |
| |
| // ScrollUpdate, at t=15, finger_pos=15px. |
| event_time = MillisecondsToTimeTicks(15); |
| frame_time = MillisecondsToTimeTicks(20); |
| SyntheticTouchScrollUpdateLatencyInfo(event_time, frame_time, |
| 10 /* scroll_delta */); |
| |
| // ScrollUpdate, at t=25, finger_pos=25px. |
| event_time = MillisecondsToTimeTicks(25); |
| frame_time = MillisecondsToTimeTicks(30); |
| SyntheticTouchScrollUpdateLatencyInfo(event_time, frame_time, |
| 10 /* scroll_delta */); |
| |
| // Another ScrollBegin to flush unfinished frames. |
| event_time = MillisecondsToTimeTicks(1000); |
| frame_time = MillisecondsToTimeTicks(1000); |
| SyntheticTouchScrollBeginLatencyInfo(event_time, frame_time, 0); |
| |
| // Prediction hasn't take affect on ScrollBegin so it'll stay the same. |
| EXPECT_THAT(histogram_tester().GetAllSamples( |
| "Event.Latency.ScrollBegin.Touch.AverageLag"), |
| ElementsAre(Bucket(7, 1))); |
| // At t=10, finger_pos = 10px, rendered_pos = 5px. |
| // At t=20, finger_pos = 20px, rendered_pos = 15px. |
| // At t=30, finger_pos = 25px, rendered_pos = 25px. |
| // AverageLag = ((5px+15px)*10ms/2 + (5px+10px)*5ms/2 + 10px*5ms)/20ms |
| // = 9.375 |
| EXPECT_THAT(histogram_tester().GetAllSamples( |
| "Event.Latency.ScrollUpdate.Touch.AverageLag"), |
| ElementsAre(Bucket(9, 1))); |
| } |
| |
| // Test AverageLag with perfect scroll prediction. |
| TEST_F(AverageLagTrackerTest, ScrollPrediction) { |
| // ScrollBegin, at t=5, finger_pos=5px. |
| // Predict frame_time=10, predicted_pos = 10px. |
| base::TimeTicks event_time = MillisecondsToTimeTicks(5); |
| base::TimeTicks frame_time = MillisecondsToTimeTicks(10); |
| SyntheticTouchScrollBeginLatencyInfo( |
| event_time, frame_time, 5 /* scroll_delta */, 10 /* predicted_delta */); |
| |
| // ScrollUpdate, at t=15, finger_pos=15px. |
| // Predict frame_time=20, predicted_pos = 20px. |
| event_time = MillisecondsToTimeTicks(15); |
| frame_time = MillisecondsToTimeTicks(20); |
| SyntheticTouchScrollUpdateLatencyInfo( |
| event_time, frame_time, 10 /* scroll_delta */, 10 /* predicted_delta */); |
| |
| // ScrollUpdate, at t=25, finger_pos=25px. |
| // Predict frame_time=30, predicted_pos = 30px. |
| event_time = MillisecondsToTimeTicks(25); |
| frame_time = MillisecondsToTimeTicks(30); |
| SyntheticTouchScrollUpdateLatencyInfo( |
| event_time, frame_time, 10 /* scroll_delta */, 10 /* predicted_delta */); |
| |
| // Another ScrollBegin to flush unfinished frames. |
| event_time = MillisecondsToTimeTicks(1000); |
| frame_time = MillisecondsToTimeTicks(1000); |
| SyntheticTouchScrollBeginLatencyInfo(event_time, frame_time, 0); |
| |
| // Prediction hasn't take affect on ScrollBegin so it'll stay the same. |
| EXPECT_THAT(histogram_tester().GetAllSamples( |
| "Event.Latency.ScrollBegin.Touch.AverageLag"), |
| ElementsAre(Bucket(7, 1))); |
| // At t=10, finger_pos = 10px, rendered_pos = 10px. |
| // At t=20, finger_pos = 20px, rendered_pos = 20px. |
| // At t=30, finger_pos = 25px, rendered_pos = 30px. |
| // AverageLag = ((0px+10px)*10ms/2 + (0px+5px)*10ms/2 + 5px*5ms)/20ms |
| // = 4.375px |
| // AverageLag (w/o prediction) |
| // ((5px+15px)*10ms/2 + (5px+10px)*5ms/2 + 10px*5ms)/20ms |
| // = 9.375px |
| // Positive effect of prediction = 5px |
| EXPECT_THAT(histogram_tester().GetAllSamples( |
| "Event.Latency.ScrollUpdate.Touch.AverageLag"), |
| ElementsAre(Bucket(4, 1))); |
| EXPECT_THAT( |
| histogram_tester().GetAllSamples( |
| "Event.Latency.ScrollUpdate.Touch.AverageLag.PredictionPositive"), |
| ElementsAre(Bucket(5, 1))); |
| histogram_tester().ExpectTotalCount( |
| "Event.Latency.ScrollUpdate.Touch.AverageLag.PredictionNegative", 0); |
| } |
| |
| // Test AverageLag with imperfect scroll prediction. |
| TEST_F(AverageLagTrackerTest, ImperfectScrollPrediction) { |
| // ScrollBegin, at t=5, finger_pos=5px. |
| // Predict frame_time=10, predicted_pos(over) = 12px. |
| base::TimeTicks event_time = MillisecondsToTimeTicks(5); |
| base::TimeTicks frame_time = MillisecondsToTimeTicks(10); |
| SyntheticTouchScrollBeginLatencyInfo( |
| event_time, frame_time, 5 /* scroll_delta */, 12 /* predicted_delta */); |
| |
| // ScrollUpdate, at t=15, finger_pos=15px. |
| // Predict frame_time=20, predicted_pos(under) = 17px. |
| event_time = MillisecondsToTimeTicks(15); |
| frame_time = MillisecondsToTimeTicks(20); |
| SyntheticTouchScrollUpdateLatencyInfo( |
| event_time, frame_time, 10 /* scroll_delta */, 5 /* predicted_delta */); |
| |
| // ScrollUpdate, at t=25, finger_pos=25px. |
| // Predict frame_time=30, predicted_pos(over) = 31px. |
| event_time = MillisecondsToTimeTicks(25); |
| frame_time = MillisecondsToTimeTicks(30); |
| SyntheticTouchScrollUpdateLatencyInfo( |
| event_time, frame_time, 10 /* scroll_delta */, 14 /* predicted_delta */); |
| |
| // Another ScrollBegin to flush unfinished frames. |
| event_time = MillisecondsToTimeTicks(1000); |
| frame_time = MillisecondsToTimeTicks(1000); |
| SyntheticTouchScrollBeginLatencyInfo(event_time, frame_time, 0); |
| |
| EXPECT_THAT(histogram_tester().GetAllSamples( |
| "Event.Latency.ScrollBegin.Touch.AverageLag"), |
| ElementsAre(Bucket(7, 1))); |
| // AverageLag = ((2px*2ms/2+8px*8ms/2)+ ((3px+8px)*5ms/2+8px*5ms))/20ms |
| // = 5.075px |
| EXPECT_THAT(histogram_tester().GetAllSamples( |
| "Event.Latency.ScrollUpdate.Touch.AverageLag"), |
| ElementsAre(Bucket(5, 1))); |
| // AverageLag (w/o prediction = |
| // ((5px+15px)*10ms/2 + (5px+10px)*5ms/2 + 10px*5ms)/20ms |
| // = 9.375px |
| // Positive effect of prediction = 4.3px |
| EXPECT_THAT( |
| histogram_tester().GetAllSamples( |
| "Event.Latency.ScrollUpdate.Touch.AverageLag.PredictionPositive"), |
| ElementsAre(Bucket(4, 1))); |
| histogram_tester().ExpectTotalCount( |
| "Event.Latency.ScrollUpdate.Touch.AverageLag.PredictionNegative", 0); |
| } |
| |
| TEST_F(AverageLagTrackerTest, NegativePredictionEffect) { |
| // ScrollBegin, at t=5, finger_pos=5px. |
| // Predict frame_time=10, predicted_pos(over) = 20px. |
| base::TimeTicks event_time = MillisecondsToTimeTicks(5); |
| base::TimeTicks frame_time = MillisecondsToTimeTicks(10); |
| SyntheticTouchScrollBeginLatencyInfo( |
| event_time, frame_time, 5 /* scroll_delta */, 20 /* predicted_delta */); |
| |
| // ScrollUpdate, at t=15, finger_pos=15px. |
| // Predict frame_time=20, predicted_pos(over) = 60px. |
| event_time = MillisecondsToTimeTicks(15); |
| frame_time = MillisecondsToTimeTicks(20); |
| SyntheticTouchScrollUpdateLatencyInfo( |
| event_time, frame_time, 10 /* scroll_delta */, 40 /* predicted_delta */); |
| |
| // ScrollUpdate, at t=25, finger_pos=25px. |
| // Predict frame_time=30, predicted_pos(over) = 60px. |
| event_time = MillisecondsToTimeTicks(25); |
| frame_time = MillisecondsToTimeTicks(30); |
| SyntheticTouchScrollUpdateLatencyInfo( |
| event_time, frame_time, 10 /* scroll_delta */, 0 /* predicted_delta */); |
| |
| // Another ScrollBegin to flush unfinished frames. |
| event_time = MillisecondsToTimeTicks(1000); |
| frame_time = MillisecondsToTimeTicks(1000); |
| SyntheticTouchScrollBeginLatencyInfo(event_time, frame_time, 0); |
| |
| EXPECT_THAT(histogram_tester().GetAllSamples( |
| "Event.Latency.ScrollBegin.Touch.AverageLag"), |
| ElementsAre(Bucket(7, 1))); |
| // AverageLag = ((10px+0px)*10ms/2)+ ((40px+35px)*5ms/2+35px*5ms))/20ms |
| // = 20.625px |
| EXPECT_THAT(histogram_tester().GetAllSamples( |
| "Event.Latency.ScrollUpdate.Touch.AverageLag"), |
| ElementsAre(Bucket(20, 1))); |
| // AverageLag (w/o prediction = |
| // ((5px+15px)*10ms/2 + (5px+10px)*5ms/2 + 10px*5ms)/20ms |
| // = 9.375px |
| // Negative effect of prediction = 11.25 |
| histogram_tester().ExpectTotalCount( |
| "Event.Latency.ScrollUpdate.Touch.AverageLag.PredictionPositive", 0); |
| EXPECT_THAT( |
| histogram_tester().GetAllSamples( |
| "Event.Latency.ScrollUpdate.Touch.AverageLag.PredictionNegative"), |
| ElementsAre(Bucket(11, 1))); |
| } |
| |
| TEST_F(AverageLagTrackerTest, NoPredictionEffect) { |
| // ScrollBegin, at t=5, finger_pos=5px. |
| // Predict frame_time=10, predicted_pos(over) = 25px. |
| base::TimeTicks event_time = MillisecondsToTimeTicks(5); |
| base::TimeTicks frame_time = MillisecondsToTimeTicks(10); |
| SyntheticTouchScrollBeginLatencyInfo( |
| event_time, frame_time, 5 /* scroll_delta */, 25 /* predicted_delta */); |
| |
| // ScrollUpdate, at t=15, finger_pos=15px. |
| // Predict frame_time=20, predicted_pos(over) = 32px. |
| event_time = MillisecondsToTimeTicks(15); |
| frame_time = MillisecondsToTimeTicks(20); |
| SyntheticTouchScrollUpdateLatencyInfo( |
| event_time, frame_time, 10 /* scroll_delta */, 7 /* predicted_delta */); |
| |
| // ScrollUpdate, at t=25, finger_pos=25px. |
| // Predict frame_time=30, predicted_pos(over) = 37px. |
| event_time = MillisecondsToTimeTicks(25); |
| frame_time = MillisecondsToTimeTicks(30); |
| SyntheticTouchScrollUpdateLatencyInfo( |
| event_time, frame_time, 10 /* scroll_delta */, 5 /* predicted_delta */); |
| |
| // Another ScrollBegin to flush unfinished frames. |
| event_time = MillisecondsToTimeTicks(1000); |
| frame_time = MillisecondsToTimeTicks(1000); |
| SyntheticTouchScrollBeginLatencyInfo(event_time, frame_time, 0); |
| |
| EXPECT_THAT(histogram_tester().GetAllSamples( |
| "Event.Latency.ScrollBegin.Touch.AverageLag"), |
| ElementsAre(Bucket(7, 1))); |
| // AverageLag = ((15px+5px)*10ms/2 + (12px+7px)*5ms/2 + 7px*5ms)/20ms |
| // = 9.125px |
| EXPECT_THAT(histogram_tester().GetAllSamples( |
| "Event.Latency.ScrollUpdate.Touch.AverageLag"), |
| ElementsAre(Bucket(9, 1))); |
| // AverageLag (w/o prediction) = |
| // ((5px+15px)*10ms/2 + (5px+10px)*5ms/2 + 10px*5ms)/20ms |
| // = 9.375px |
| // Prediction slightly positive, we should see a 0 bucket in |
| // PredictionPositive UMA |
| EXPECT_THAT( |
| histogram_tester().GetAllSamples( |
| "Event.Latency.ScrollUpdate.Touch.AverageLag.PredictionPositive"), |
| ElementsAre(Bucket(0, 1))); |
| histogram_tester().ExpectTotalCount( |
| "Event.Latency.ScrollUpdate.Touch.AverageLag.PredictionNegative", 0); |
| } |
| |
| } // namespace |
| } // namespace ui |
