ui/latency/latency_tracker.cc - chromium/src - Git at Google

 // Copyright 2017 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/latency_tracker.h"

 #include <algorithm>
 #include "base/metrics/histogram_functions.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/no_destructor.h"
 #include "base/rand_util.h"
 #include "base/trace_event/trace_event.h"
 #include "services/metrics/public/cpp/ukm_entry_builder.h"
 #include "services/metrics/public/cpp/ukm_recorder.h"
 #include "ui/latency/latency_histogram_macros.h"

 // Impose some restrictions for tests etc, but also be lenient since some of the
 // data come from untrusted sources.
 #define DCHECK_AND_RETURN_ON_FAIL(x) \
   DCHECK(x);                         \
   if (!(x))                          \
     return;

 namespace ui {
 namespace {

 std::string LatencySourceEventTypeToInputModalityString(
     ui::SourceEventType type) {
   switch (type) {
     case ui::SourceEventType::WHEEL:
       return "Wheel";
     case ui::SourceEventType::MOUSE:
       return "Mouse";
     case ui::SourceEventType::TOUCH:
     case ui::SourceEventType::INERTIAL:
       return "Touch";
     case ui::SourceEventType::KEY_PRESS:
       return "KeyPress";
     case ui::SourceEventType::TOUCHPAD:
       return "Touchpad";
     default:
       return "";
   }
 }

 bool IsInertialScroll(const LatencyInfo& latency) {
   return latency.source_event_type() == ui::SourceEventType::INERTIAL;
 }

 // This UMA metric tracks the time from when the original wheel event is created
 // to when the scroll gesture results in final frame swap. All scroll events are
 // included in this metric.
 void RecordUmaEventLatencyScrollWheelTimeToScrollUpdateSwapBegin2Histogram(
     base::TimeTicks start,
     base::TimeTicks end) {
   CONFIRM_EVENT_TIMES_EXIST(start, end);
   UMA_HISTOGRAM_CUSTOM_COUNTS(
       "Event.Latency.Scroll.Wheel.TimeToScrollUpdateSwapBegin2",
       std::max(static_cast<int64_t>(0), (end - start).InMicroseconds()), 1,
       1000000, 100);
 }

 LatencyTracker::LatencyInfoProcessor& GetLatencyInfoProcessor() {
   static base::NoDestructor<LatencyTracker::LatencyInfoProcessor> processor;
   return *processor;
 }

 bool LatencyTraceIdCompare(const LatencyInfo& i, const LatencyInfo& j) {
   return i.trace_id() < j.trace_id();
 }

 }  // namespace

 LatencyTracker::LatencyTracker() = default;
 LatencyTracker::~LatencyTracker() = default;

 void LatencyTracker::OnGpuSwapBuffersCompleted(
     const std::vector<ui::LatencyInfo>& latency_info) {
   auto& callback = GetLatencyInfoProcessor();
   if (!callback.is_null())
     callback.Run(latency_info);
   // Sort latency_info as they can be in incorrect order.
   std::vector<ui::LatencyInfo> latency_infos(latency_info);
   std::sort(latency_infos.begin(), latency_infos.end(), LatencyTraceIdCompare);
   for (const auto& latency : latency_infos)
     OnGpuSwapBuffersCompleted(latency);
 }

 void LatencyTracker::OnGpuSwapBuffersCompleted(const LatencyInfo& latency) {
   base::TimeTicks gpu_swap_end_timestamp;
   if (!latency.FindLatency(INPUT_EVENT_LATENCY_FRAME_SWAP_COMPONENT,
                            &gpu_swap_end_timestamp)) {
     return;
   }

   base::TimeTicks gpu_swap_begin_timestamp;
   bool found_component = latency.FindLatency(
       ui::INPUT_EVENT_GPU_SWAP_BUFFER_COMPONENT, &gpu_swap_begin_timestamp);
   DCHECK_AND_RETURN_ON_FAIL(found_component);

   if (!latency.FindLatency(ui::INPUT_EVENT_LATENCY_BEGIN_RWH_COMPONENT,
                            nullptr)) {
     return;
   }

   ui::SourceEventType source_event_type = latency.source_event_type();
   if (source_event_type == ui::SourceEventType::WHEEL ||
       source_event_type == ui::SourceEventType::MOUSE ||
       source_event_type == ui::SourceEventType::TOUCH ||
       source_event_type == ui::SourceEventType::INERTIAL ||
       source_event_type == ui::SourceEventType::KEY_PRESS ||
       source_event_type == ui::SourceEventType::TOUCHPAD) {
     ComputeEndToEndLatencyHistograms(gpu_swap_begin_timestamp,
                                      gpu_swap_end_timestamp, latency);
   }
 }

 void LatencyTracker::ReportUkmScrollLatency(
     const InputMetricEvent& metric_event,
     base::TimeTicks start_timestamp,
     base::TimeTicks time_to_scroll_update_swap_begin_timestamp,
     base::TimeTicks time_to_handled_timestamp,
     bool is_main_thread,
     const ukm::SourceId ukm_source_id) {
   CONFIRM_EVENT_TIMES_EXIST(start_timestamp,
                             time_to_scroll_update_swap_begin_timestamp)
   CONFIRM_EVENT_TIMES_EXIST(start_timestamp, time_to_handled_timestamp)

   ukm::UkmRecorder* ukm_recorder = ukm::UkmRecorder::Get();
   if (ukm_source_id == ukm::kInvalidSourceId || !ukm_recorder)
     return;

   std::string event_name = "";
   switch (metric_event) {
     case InputMetricEvent::SCROLL_BEGIN_TOUCH:
       event_name = "Event.ScrollBegin.Touch";
       break;
     case InputMetricEvent::SCROLL_UPDATE_TOUCH:
       event_name = "Event.ScrollUpdate.Touch";
       break;
     case InputMetricEvent::SCROLL_BEGIN_WHEEL:
       event_name = "Event.ScrollBegin.Wheel";
       break;
     case InputMetricEvent::SCROLL_UPDATE_WHEEL:
       event_name = "Event.ScrollUpdate.Wheel";
       break;
   }

   ukm::UkmEntryBuilder builder(ukm_source_id, event_name.c_str());
   builder.SetMetric(
       "TimeToScrollUpdateSwapBegin",
       std::max(static_cast<int64_t>(0),
                (time_to_scroll_update_swap_begin_timestamp - start_timestamp)
                    .InMicroseconds()));
   builder.SetMetric(
       "TimeToHandled",
       std::max(static_cast<int64_t>(0),
                (time_to_handled_timestamp - start_timestamp).InMicroseconds()));
   builder.SetMetric("IsMainThread", is_main_thread);
   builder.Record(ukm_recorder);
 }

 void LatencyTracker::ComputeEndToEndLatencyHistograms(
     base::TimeTicks gpu_swap_begin_timestamp,
     base::TimeTicks gpu_swap_end_timestamp,
     const ui::LatencyInfo& latency) {
   DCHECK_AND_RETURN_ON_FAIL(!latency.coalesced());

   base::TimeTicks original_timestamp;
   std::string scroll_name = "Uninitialized";

   const std::string input_modality =
       LatencySourceEventTypeToInputModalityString(latency.source_event_type());

   if (latency.FindLatency(
           ui::INPUT_EVENT_LATENCY_FIRST_SCROLL_UPDATE_ORIGINAL_COMPONENT,
           &original_timestamp)) {
     DCHECK(input_modality == "Wheel" || input_modality == "Touch");

     // For inertial scrolling we don't separate the first event from the rest of
     // them.
     scroll_name = IsInertialScroll(latency) ? "ScrollInertial" : "ScrollBegin";

     // This UMA metric tracks the performance of overall scrolling as a high
     // level metric.
     UMA_HISTOGRAM_INPUT_LATENCY_5_SECONDS_MAX_MICROSECONDS(
         "Event.Latency.ScrollBegin.TimeToScrollUpdateSwapBegin2",
         original_timestamp, gpu_swap_begin_timestamp);

     // This UMA metric tracks the time between the final frame swap for the
     // first scroll event in a sequence and the original timestamp of that
     // scroll event's underlying touch/wheel event.
     UMA_HISTOGRAM_INPUT_LATENCY_5_SECONDS_MAX_MICROSECONDS(
         "Event.Latency." + scroll_name + "." + input_modality +
             ".TimeToScrollUpdateSwapBegin4",
         original_timestamp, gpu_swap_begin_timestamp);

     if (input_modality == "Wheel") {
       RecordUmaEventLatencyScrollWheelTimeToScrollUpdateSwapBegin2Histogram(
           original_timestamp, gpu_swap_begin_timestamp);
     }

   } else if (latency.FindLatency(
                  ui::INPUT_EVENT_LATENCY_SCROLL_UPDATE_ORIGINAL_COMPONENT,
                  &original_timestamp)) {
     DCHECK(input_modality == "Wheel" || input_modality == "Touch");

     // For inertial scrolling we don't separate the first event from the rest of
     // them.
     scroll_name = IsInertialScroll(latency) ? "ScrollInertial" : "ScrollUpdate";

     // This UMA metric tracks the performance of overall scrolling as a high
     // level metric.
     UMA_HISTOGRAM_INPUT_LATENCY_5_SECONDS_MAX_MICROSECONDS(
         "Event.Latency.ScrollUpdate.TimeToScrollUpdateSwapBegin2",
         original_timestamp, gpu_swap_begin_timestamp);

     // This UMA metric tracks the time from when the original touch/wheel event
     // is created to when the scroll gesture results in final frame swap.
     // First scroll events are excluded from this metric.
     UMA_HISTOGRAM_INPUT_LATENCY_5_SECONDS_MAX_MICROSECONDS(
         "Event.Latency." + scroll_name + "." + input_modality +
             ".TimeToScrollUpdateSwapBegin4",
         original_timestamp, gpu_swap_begin_timestamp);

     if (input_modality == "Wheel") {
       RecordUmaEventLatencyScrollWheelTimeToScrollUpdateSwapBegin2Histogram(
           original_timestamp, gpu_swap_begin_timestamp);
     }
   } else if (latency.FindLatency(ui::INPUT_EVENT_LATENCY_ORIGINAL_COMPONENT,
                                  &original_timestamp)) {
     if (latency.source_event_type() == SourceEventType::KEY_PRESS) {
       UMA_HISTOGRAM_INPUT_LATENCY_HIGH_RESOLUTION_MICROSECONDS(
           "Event.Latency.EndToEnd.KeyPress", original_timestamp,
           gpu_swap_begin_timestamp);
     } else if (latency.source_event_type() == SourceEventType::MOUSE) {
       UMA_HISTOGRAM_INPUT_LATENCY_HIGH_RESOLUTION_MICROSECONDS(
           "Event.Latency.EndToEnd.Mouse", original_timestamp,
           gpu_swap_begin_timestamp);
     } else if (latency.source_event_type() == SourceEventType::TOUCHPAD) {
       base::TimeTicks timestamp;
       if (latency.FindLatency(ui::INPUT_EVENT_LATENCY_BEGIN_RWH_COMPONENT,
                               &timestamp)) {
         UMA_HISTOGRAM_INPUT_LATENCY_CUSTOM_MICROSECONDS(
             "Event.Latency.EventToRender.TouchpadPinch", original_timestamp,
             timestamp);
       }
       UMA_HISTOGRAM_INPUT_LATENCY_CUSTOM_MICROSECONDS(
           "Event.Latency.EndToEnd.TouchpadPinch", original_timestamp,
           gpu_swap_begin_timestamp);
     }
     return;
   } else {
     // No original component found.
     return;
   }

   // Record scroll latency metrics.
   DCHECK(scroll_name == "ScrollBegin" || scroll_name == "ScrollUpdate" ||
          (IsInertialScroll(latency) && scroll_name == "ScrollInertial"));

   if (!IsInertialScroll(latency) && input_modality == "Touch")
     average_lag_tracker_.AddLatencyInFrame(latency, gpu_swap_begin_timestamp,
                                            scroll_name);

   base::TimeTicks rendering_scheduled_timestamp;
   bool rendering_scheduled_on_main = latency.FindLatency(
       ui::INPUT_EVENT_LATENCY_RENDERING_SCHEDULED_MAIN_COMPONENT,
       &rendering_scheduled_timestamp);
   if (!rendering_scheduled_on_main) {
     bool found_component = latency.FindLatency(
         ui::INPUT_EVENT_LATENCY_RENDERING_SCHEDULED_IMPL_COMPONENT,
         &rendering_scheduled_timestamp);
     DCHECK_AND_RETURN_ON_FAIL(found_component);
   }

   // Inertial scrolls are excluded from Ukm metrics.
   if ((input_modality == "Touch" && !IsInertialScroll(latency)) ||
       input_modality == "Wheel") {
     InputMetricEvent input_metric_event;
     if (scroll_name == "ScrollBegin") {
       input_metric_event = input_modality == "Touch"
                                ? InputMetricEvent::SCROLL_BEGIN_TOUCH
                                : InputMetricEvent::SCROLL_BEGIN_WHEEL;
     } else {
       DCHECK_EQ(scroll_name, "ScrollUpdate");
       input_metric_event = input_modality == "Touch"
                                ? InputMetricEvent::SCROLL_UPDATE_TOUCH
                                : InputMetricEvent::SCROLL_UPDATE_WHEEL;
     }
     ReportUkmScrollLatency(
         input_metric_event, original_timestamp, gpu_swap_begin_timestamp,
         rendering_scheduled_timestamp, rendering_scheduled_on_main,
         latency.ukm_source_id());
   }

   const std::string thread_name = rendering_scheduled_on_main ? "Main" : "Impl";

   UMA_HISTOGRAM_SCROLL_LATENCY_LONG_2(
       "Event.Latency." + scroll_name + "." + input_modality +
           ".TimeToHandled2_" + thread_name,
       original_timestamp, rendering_scheduled_timestamp);

   if (input_modality == "Wheel") {
     UMA_HISTOGRAM_SCROLL_LATENCY_LONG_2(
         "Event.Latency.Scroll.Wheel.TimeToHandled2_" + thread_name,
         original_timestamp, rendering_scheduled_timestamp);
   }

   base::TimeTicks renderer_swap_timestamp;
   bool found_renderer_swap_component =
       latency.FindLatency(ui::INPUT_EVENT_LATENCY_RENDERER_SWAP_COMPONENT,
                           &renderer_swap_timestamp);

   base::TimeTicks browser_received_swap_timestamp;
   bool found_received_frame_component =
       latency.FindLatency(ui::DISPLAY_COMPOSITOR_RECEIVED_FRAME_COMPONENT,
                           &browser_received_swap_timestamp);
   DCHECK_AND_RETURN_ON_FAIL(found_received_frame_component);

   // If we're committing to the active tree, there will never be a renderer
   // swap. In this case, don't record the two histogram values for the periods
   // surrounding the renderer swap. We could assign the total time to one or the
   // other of them, but that would likely skew statistics.
   if (found_renderer_swap_component) {
     UMA_HISTOGRAM_SCROLL_LATENCY_LONG_2(
         "Event.Latency." + scroll_name + "." + input_modality +
             ".HandledToRendererSwap2_" + thread_name,
         rendering_scheduled_timestamp, renderer_swap_timestamp);

     UMA_HISTOGRAM_SCROLL_LATENCY_SHORT_2(
         "Event.Latency." + scroll_name + "." + input_modality +
             ".RendererSwapToBrowserNotified2",
         renderer_swap_timestamp, browser_received_swap_timestamp);
   }

   UMA_HISTOGRAM_SCROLL_LATENCY_LONG_2(
       "Event.Latency." + scroll_name + "." + input_modality +
           ".BrowserNotifiedToBeforeGpuSwap2",
       browser_received_swap_timestamp, gpu_swap_begin_timestamp);

   UMA_HISTOGRAM_SCROLL_LATENCY_SHORT_2(
       "Event.Latency." + scroll_name + "." + input_modality + ".GpuSwap2",
       gpu_swap_begin_timestamp, gpu_swap_end_timestamp);
 }

 // static
 void LatencyTracker::SetLatencyInfoProcessorForTesting(
     const LatencyInfoProcessor& processor) {
   GetLatencyInfoProcessor() = processor;
 }

 }  // namespace ui
	// Copyright 2017 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/latency_tracker.h"

	#include <algorithm>
	#include "base/metrics/histogram_functions.h"
	#include "base/metrics/histogram_macros.h"
	#include "base/no_destructor.h"
	#include "base/rand_util.h"
	#include "base/trace_event/trace_event.h"
	#include "services/metrics/public/cpp/ukm_entry_builder.h"
	#include "services/metrics/public/cpp/ukm_recorder.h"
	#include "ui/latency/latency_histogram_macros.h"

	// Impose some restrictions for tests etc, but also be lenient since some of the
	// data come from untrusted sources.
	#define DCHECK_AND_RETURN_ON_FAIL(x) \
	DCHECK(x); \
	if (!(x)) \
	return;

	namespace ui {
	namespace {

	std::string LatencySourceEventTypeToInputModalityString(
	ui::SourceEventType type) {
	switch (type) {
	case ui::SourceEventType::WHEEL:
	return "Wheel";
	case ui::SourceEventType::MOUSE:
	return "Mouse";
	case ui::SourceEventType::TOUCH:
	case ui::SourceEventType::INERTIAL:
	return "Touch";
	case ui::SourceEventType::KEY_PRESS:
	return "KeyPress";
	case ui::SourceEventType::TOUCHPAD:
	return "Touchpad";
	default:
	return "";
	}
	}

	bool IsInertialScroll(const LatencyInfo& latency) {
	return latency.source_event_type() == ui::SourceEventType::INERTIAL;
	}

	// This UMA metric tracks the time from when the original wheel event is created
	// to when the scroll gesture results in final frame swap. All scroll events are
	// included in this metric.
	void RecordUmaEventLatencyScrollWheelTimeToScrollUpdateSwapBegin2Histogram(
	base::TimeTicks start,
	base::TimeTicks end) {
	CONFIRM_EVENT_TIMES_EXIST(start, end);
	UMA_HISTOGRAM_CUSTOM_COUNTS(
	"Event.Latency.Scroll.Wheel.TimeToScrollUpdateSwapBegin2",
	std::max(static_cast<int64_t>(0), (end - start).InMicroseconds()), 1,
	1000000, 100);
	}

	LatencyTracker::LatencyInfoProcessor& GetLatencyInfoProcessor() {
	static base::NoDestructor<LatencyTracker::LatencyInfoProcessor> processor;
	return *processor;
	}

	bool LatencyTraceIdCompare(const LatencyInfo& i, const LatencyInfo& j) {
	return i.trace_id() < j.trace_id();
	}

	} // namespace

	LatencyTracker::LatencyTracker() = default;
	LatencyTracker::~LatencyTracker() = default;

	void LatencyTracker::OnGpuSwapBuffersCompleted(
	const std::vector<ui::LatencyInfo>& latency_info) {
	auto& callback = GetLatencyInfoProcessor();
	if (!callback.is_null())
	callback.Run(latency_info);
	// Sort latency_info as they can be in incorrect order.
	std::vector<ui::LatencyInfo> latency_infos(latency_info);
	std::sort(latency_infos.begin(), latency_infos.end(), LatencyTraceIdCompare);
	for (const auto& latency : latency_infos)
	OnGpuSwapBuffersCompleted(latency);
	}

	void LatencyTracker::OnGpuSwapBuffersCompleted(const LatencyInfo& latency) {
	base::TimeTicks gpu_swap_end_timestamp;
	if (!latency.FindLatency(INPUT_EVENT_LATENCY_FRAME_SWAP_COMPONENT,
	&gpu_swap_end_timestamp)) {
	return;
	}

	base::TimeTicks gpu_swap_begin_timestamp;
	bool found_component = latency.FindLatency(
	ui::INPUT_EVENT_GPU_SWAP_BUFFER_COMPONENT, &gpu_swap_begin_timestamp);
	DCHECK_AND_RETURN_ON_FAIL(found_component);

	if (!latency.FindLatency(ui::INPUT_EVENT_LATENCY_BEGIN_RWH_COMPONENT,
	nullptr)) {
	return;
	}

	ui::SourceEventType source_event_type = latency.source_event_type();
	if (source_event_type == ui::SourceEventType::WHEEL \|\|
	source_event_type == ui::SourceEventType::MOUSE \|\|
	source_event_type == ui::SourceEventType::TOUCH \|\|
	source_event_type == ui::SourceEventType::INERTIAL \|\|
	source_event_type == ui::SourceEventType::KEY_PRESS \|\|
	source_event_type == ui::SourceEventType::TOUCHPAD) {
	ComputeEndToEndLatencyHistograms(gpu_swap_begin_timestamp,
	gpu_swap_end_timestamp, latency);
	}
	}

	void LatencyTracker::ReportUkmScrollLatency(
	const InputMetricEvent& metric_event,
	base::TimeTicks start_timestamp,
	base::TimeTicks time_to_scroll_update_swap_begin_timestamp,
	base::TimeTicks time_to_handled_timestamp,
	bool is_main_thread,
	const ukm::SourceId ukm_source_id) {
	CONFIRM_EVENT_TIMES_EXIST(start_timestamp,
	time_to_scroll_update_swap_begin_timestamp)
	CONFIRM_EVENT_TIMES_EXIST(start_timestamp, time_to_handled_timestamp)

	ukm::UkmRecorder* ukm_recorder = ukm::UkmRecorder::Get();
	if (ukm_source_id == ukm::kInvalidSourceId \|\| !ukm_recorder)
	return;

	std::string event_name = "";
	switch (metric_event) {
	case InputMetricEvent::SCROLL_BEGIN_TOUCH:
	event_name = "Event.ScrollBegin.Touch";
	break;
	case InputMetricEvent::SCROLL_UPDATE_TOUCH:
	event_name = "Event.ScrollUpdate.Touch";
	break;
	case InputMetricEvent::SCROLL_BEGIN_WHEEL:
	event_name = "Event.ScrollBegin.Wheel";
	break;
	case InputMetricEvent::SCROLL_UPDATE_WHEEL:
	event_name = "Event.ScrollUpdate.Wheel";
	break;
	}

	ukm::UkmEntryBuilder builder(ukm_source_id, event_name.c_str());
	builder.SetMetric(
	"TimeToScrollUpdateSwapBegin",
	std::max(static_cast<int64_t>(0),
	(time_to_scroll_update_swap_begin_timestamp - start_timestamp)
	.InMicroseconds()));
	builder.SetMetric(
	"TimeToHandled",
	std::max(static_cast<int64_t>(0),
	(time_to_handled_timestamp - start_timestamp).InMicroseconds()));
	builder.SetMetric("IsMainThread", is_main_thread);
	builder.Record(ukm_recorder);
	}

	void LatencyTracker::ComputeEndToEndLatencyHistograms(
	base::TimeTicks gpu_swap_begin_timestamp,
	base::TimeTicks gpu_swap_end_timestamp,
	const ui::LatencyInfo& latency) {
	DCHECK_AND_RETURN_ON_FAIL(!latency.coalesced());

	base::TimeTicks original_timestamp;
	std::string scroll_name = "Uninitialized";

	const std::string input_modality =
	LatencySourceEventTypeToInputModalityString(latency.source_event_type());

	if (latency.FindLatency(
	ui::INPUT_EVENT_LATENCY_FIRST_SCROLL_UPDATE_ORIGINAL_COMPONENT,
	&original_timestamp)) {
	DCHECK(input_modality == "Wheel" \|\| input_modality == "Touch");

	// For inertial scrolling we don't separate the first event from the rest of
	// them.
	scroll_name = IsInertialScroll(latency) ? "ScrollInertial" : "ScrollBegin";

	// This UMA metric tracks the performance of overall scrolling as a high
	// level metric.
	UMA_HISTOGRAM_INPUT_LATENCY_5_SECONDS_MAX_MICROSECONDS(
	"Event.Latency.ScrollBegin.TimeToScrollUpdateSwapBegin2",
	original_timestamp, gpu_swap_begin_timestamp);

	// This UMA metric tracks the time between the final frame swap for the
	// first scroll event in a sequence and the original timestamp of that
	// scroll event's underlying touch/wheel event.
	UMA_HISTOGRAM_INPUT_LATENCY_5_SECONDS_MAX_MICROSECONDS(
	"Event.Latency." + scroll_name + "." + input_modality +
	".TimeToScrollUpdateSwapBegin4",
	original_timestamp, gpu_swap_begin_timestamp);

	if (input_modality == "Wheel") {
	RecordUmaEventLatencyScrollWheelTimeToScrollUpdateSwapBegin2Histogram(
	original_timestamp, gpu_swap_begin_timestamp);
	}

	} else if (latency.FindLatency(
	ui::INPUT_EVENT_LATENCY_SCROLL_UPDATE_ORIGINAL_COMPONENT,
	&original_timestamp)) {
	DCHECK(input_modality == "Wheel" \|\| input_modality == "Touch");

	// For inertial scrolling we don't separate the first event from the rest of
	// them.
	scroll_name = IsInertialScroll(latency) ? "ScrollInertial" : "ScrollUpdate";

	// This UMA metric tracks the performance of overall scrolling as a high
	// level metric.
	UMA_HISTOGRAM_INPUT_LATENCY_5_SECONDS_MAX_MICROSECONDS(
	"Event.Latency.ScrollUpdate.TimeToScrollUpdateSwapBegin2",
	original_timestamp, gpu_swap_begin_timestamp);

	// This UMA metric tracks the time from when the original touch/wheel event
	// is created to when the scroll gesture results in final frame swap.
	// First scroll events are excluded from this metric.
	UMA_HISTOGRAM_INPUT_LATENCY_5_SECONDS_MAX_MICROSECONDS(
	"Event.Latency." + scroll_name + "." + input_modality +
	".TimeToScrollUpdateSwapBegin4",
	original_timestamp, gpu_swap_begin_timestamp);

	if (input_modality == "Wheel") {
	RecordUmaEventLatencyScrollWheelTimeToScrollUpdateSwapBegin2Histogram(
	original_timestamp, gpu_swap_begin_timestamp);
	}
	} else if (latency.FindLatency(ui::INPUT_EVENT_LATENCY_ORIGINAL_COMPONENT,
	&original_timestamp)) {
	if (latency.source_event_type() == SourceEventType::KEY_PRESS) {
	UMA_HISTOGRAM_INPUT_LATENCY_HIGH_RESOLUTION_MICROSECONDS(
	"Event.Latency.EndToEnd.KeyPress", original_timestamp,
	gpu_swap_begin_timestamp);
	} else if (latency.source_event_type() == SourceEventType::MOUSE) {
	UMA_HISTOGRAM_INPUT_LATENCY_HIGH_RESOLUTION_MICROSECONDS(
	"Event.Latency.EndToEnd.Mouse", original_timestamp,
	gpu_swap_begin_timestamp);
	} else if (latency.source_event_type() == SourceEventType::TOUCHPAD) {
	base::TimeTicks timestamp;
	if (latency.FindLatency(ui::INPUT_EVENT_LATENCY_BEGIN_RWH_COMPONENT,
	&timestamp)) {
	UMA_HISTOGRAM_INPUT_LATENCY_CUSTOM_MICROSECONDS(
	"Event.Latency.EventToRender.TouchpadPinch", original_timestamp,
	timestamp);
	}
	UMA_HISTOGRAM_INPUT_LATENCY_CUSTOM_MICROSECONDS(
	"Event.Latency.EndToEnd.TouchpadPinch", original_timestamp,
	gpu_swap_begin_timestamp);
	}
	return;
	} else {
	// No original component found.
	return;
	}

	// Record scroll latency metrics.
	DCHECK(scroll_name == "ScrollBegin" \|\| scroll_name == "ScrollUpdate" \|\|
	(IsInertialScroll(latency) && scroll_name == "ScrollInertial"));

	if (!IsInertialScroll(latency) && input_modality == "Touch")
	average_lag_tracker_.AddLatencyInFrame(latency, gpu_swap_begin_timestamp,
	scroll_name);

	base::TimeTicks rendering_scheduled_timestamp;
	bool rendering_scheduled_on_main = latency.FindLatency(
	ui::INPUT_EVENT_LATENCY_RENDERING_SCHEDULED_MAIN_COMPONENT,
	&rendering_scheduled_timestamp);
	if (!rendering_scheduled_on_main) {
	bool found_component = latency.FindLatency(
	ui::INPUT_EVENT_LATENCY_RENDERING_SCHEDULED_IMPL_COMPONENT,
	&rendering_scheduled_timestamp);
	DCHECK_AND_RETURN_ON_FAIL(found_component);
	}

	// Inertial scrolls are excluded from Ukm metrics.
	if ((input_modality == "Touch" && !IsInertialScroll(latency)) \|\|
	input_modality == "Wheel") {
	InputMetricEvent input_metric_event;
	if (scroll_name == "ScrollBegin") {
	input_metric_event = input_modality == "Touch"
	? InputMetricEvent::SCROLL_BEGIN_TOUCH
	: InputMetricEvent::SCROLL_BEGIN_WHEEL;
	} else {
	DCHECK_EQ(scroll_name, "ScrollUpdate");
	input_metric_event = input_modality == "Touch"
	? InputMetricEvent::SCROLL_UPDATE_TOUCH
	: InputMetricEvent::SCROLL_UPDATE_WHEEL;
	}
	ReportUkmScrollLatency(
	input_metric_event, original_timestamp, gpu_swap_begin_timestamp,
	rendering_scheduled_timestamp, rendering_scheduled_on_main,
	latency.ukm_source_id());
	}

	const std::string thread_name = rendering_scheduled_on_main ? "Main" : "Impl";

	UMA_HISTOGRAM_SCROLL_LATENCY_LONG_2(
	"Event.Latency." + scroll_name + "." + input_modality +
	".TimeToHandled2_" + thread_name,
	original_timestamp, rendering_scheduled_timestamp);

	if (input_modality == "Wheel") {
	UMA_HISTOGRAM_SCROLL_LATENCY_LONG_2(
	"Event.Latency.Scroll.Wheel.TimeToHandled2_" + thread_name,
	original_timestamp, rendering_scheduled_timestamp);
	}

	base::TimeTicks renderer_swap_timestamp;
	bool found_renderer_swap_component =
	latency.FindLatency(ui::INPUT_EVENT_LATENCY_RENDERER_SWAP_COMPONENT,
	&renderer_swap_timestamp);

	base::TimeTicks browser_received_swap_timestamp;
	bool found_received_frame_component =
	latency.FindLatency(ui::DISPLAY_COMPOSITOR_RECEIVED_FRAME_COMPONENT,
	&browser_received_swap_timestamp);
	DCHECK_AND_RETURN_ON_FAIL(found_received_frame_component);

	// If we're committing to the active tree, there will never be a renderer
	// swap. In this case, don't record the two histogram values for the periods
	// surrounding the renderer swap. We could assign the total time to one or the
	// other of them, but that would likely skew statistics.
	if (found_renderer_swap_component) {
	UMA_HISTOGRAM_SCROLL_LATENCY_LONG_2(
	"Event.Latency." + scroll_name + "." + input_modality +
	".HandledToRendererSwap2_" + thread_name,
	rendering_scheduled_timestamp, renderer_swap_timestamp);

	UMA_HISTOGRAM_SCROLL_LATENCY_SHORT_2(
	"Event.Latency." + scroll_name + "." + input_modality +
	".RendererSwapToBrowserNotified2",
	renderer_swap_timestamp, browser_received_swap_timestamp);
	}

	UMA_HISTOGRAM_SCROLL_LATENCY_LONG_2(
	"Event.Latency." + scroll_name + "." + input_modality +
	".BrowserNotifiedToBeforeGpuSwap2",
	browser_received_swap_timestamp, gpu_swap_begin_timestamp);

	UMA_HISTOGRAM_SCROLL_LATENCY_SHORT_2(
	"Event.Latency." + scroll_name + "." + input_modality + ".GpuSwap2",
	gpu_swap_begin_timestamp, gpu_swap_end_timestamp);
	}

	// static
	void LatencyTracker::SetLatencyInfoProcessorForTesting(
	const LatencyInfoProcessor& processor) {
	GetLatencyInfoProcessor() = processor;
	}

	} // namespace ui