desks: Add animation latency histograms

These will measure latency for the desk switch animation to start.

Bug: b/227380117
Test: ash_unittests DesksTest.AnimationLatency*
Change-Id: I49a1e75d8c647ec422d6a077778c89dea5e4613d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3564266
Reviewed-by: Tony Yeoman <tby@chromium.org>
Reviewed-by: Sammie Quon <sammiequon@chromium.org>
Reviewed-by: Ahmed Fakhry <afakhry@chromium.org>
Commit-Queue: Avery Musbach <amusbach@chromium.org>
Cr-Commit-Position: refs/heads/main@{#988196}

ash/wm/desks/desk_animation_base.cc

@@ -37,13 +37,15 @@ DeskAnimationBase::~DeskAnimationBase() {
 }
 
 void DeskAnimationBase::Launch() {
+  launch_time_ = base::TimeTicks::Now();
+
   for (auto& observer : controller_->observers_)
     observer.OnDeskSwitchAnimationLaunching();
 
   // The throughput tracker measures the animation when the user lifts their
   // fingers off the trackpad, which is done in EndSwipeAnimation.
   if (!is_continuous_gesture_animation_)
-    throughput_tracker_.Start(GetReportCallback());
+    throughput_tracker_.Start(GetSmoothnessReportCallback());
 
   // This step makes sure that the containers of the target desk are shown at
   // the beginning of the animation (but not actually visible to the user yet,
@@ -122,6 +124,11 @@ void DeskAnimationBase::OnEndingDeskScreenshotTaken() {
   if (skip_start_animation)
     return;
 
+  if (!launch_time_.is_null()) {
+    GetLatencyReportCallback().Run(base::TimeTicks::Now() - launch_time_);
+    launch_time_ = base::TimeTicks();
+  }
+
   for (auto& animator : desk_switch_animators_)
     animator->StartAnimation();
 }

ash/wm/desks/desk_animation_base.h

@@ -9,6 +9,8 @@
 #include "ash/public/cpp/metrics_util.h"
 #include "ash/wm/desks/desks_histogram_enums.h"
 #include "ash/wm/desks/root_window_desk_switch_animator.h"
+#include "base/callback.h"
+#include "base/time/time.h"
 #include "ui/compositor/throughput_tracker.h"
 
 namespace ash {
@@ -78,11 +80,13 @@ class ASH_EXPORT DeskAnimationBase
   virtual void OnDeskSwitchAnimationFinishedInternal() = 0;
 
   // Since performance here matters, we have to use the UMA histograms macros to
-  // report the smoothness histograms, but each macro use has to be associated
-  // with exactly one histogram name. This function allows subclasses to return
-  // a callback that reports the histogram using the macro with their desired
-  // name.
-  virtual metrics_util::ReportCallback GetReportCallback() const = 0;
+  // report the histograms, but each macro use has to be associated with exactly
+  // one histogram name. These functions allow subclasses to return callbacks
+  // that report each histogram using the macro with their desired name.
+  using LatencyReportCallback =
+      base::OnceCallback<void(const base::TimeDelta& latency)>;
+  virtual LatencyReportCallback GetLatencyReportCallback() const = 0;
+  virtual metrics_util::ReportCallback GetSmoothnessReportCallback() const = 0;
 
   DesksController* const controller_;
 
@@ -116,6 +120,11 @@ class ASH_EXPORT DeskAnimationBase
   // remove animation.
   int visible_desk_changes_ = 0;
 
+  // Used for the Ash.Desks.AnimationLatency.* histograms. Null if no animation
+  // is being prepared. In a continuous desk animation, the latency is reported
+  // only for the first desk switch, and `launch_time_` is null thereafter.
+  base::TimeTicks launch_time_;
+
   // ThroughputTracker used for measuring this animation smoothness.
   ui::ThroughputTracker throughput_tracker_;
 

ash/wm/desks/desk_animation_impl.cc

@@ -23,8 +23,12 @@ namespace ash {
 
 namespace {
 
+constexpr char kDeskActivationLatencyHistogramName[] =
+    "Ash.Desks.AnimationLatency.DeskActivation";
 constexpr char kDeskActivationSmoothnessHistogramName[] =
     "Ash.Desks.AnimationSmoothness.DeskActivation";
+constexpr char kDeskRemovalLatencyHistogramName[] =
+    "Ash.Desks.AnimationLatency.DeskRemoval";
 constexpr char kDeskRemovalSmoothnessHistogramName[] =
     "Ash.Desks.AnimationSmoothness.DeskRemoval";
 
@@ -261,8 +265,15 @@ void DeskActivationAnimation::OnDeskSwitchAnimationFinishedInternal() {
       update_window_activation_);
 }
 
-metrics_util::ReportCallback DeskActivationAnimation::GetReportCallback()
-    const {
+DeskAnimationBase::LatencyReportCallback
+DeskActivationAnimation::GetLatencyReportCallback() const {
+  return base::BindOnce([](const base::TimeDelta& latency) {
+    UMA_HISTOGRAM_TIMES(kDeskActivationLatencyHistogramName, latency);
+  });
+}
+
+metrics_util::ReportCallback
+DeskActivationAnimation::GetSmoothnessReportCallback() const {
   return metrics_util::ForSmoothness(base::BindRepeating([](int smoothness) {
     UMA_HISTOGRAM_PERCENTAGE(kDeskActivationSmoothnessHistogramName,
                              smoothness);
@@ -365,7 +376,15 @@ void DeskRemovalAnimation::OnDeskSwitchAnimationFinishedInternal() {
   MaybeRestoreSplitView(/*refresh_snapped_windows=*/true);
 }
 
-metrics_util::ReportCallback DeskRemovalAnimation::GetReportCallback() const {
+DeskAnimationBase::LatencyReportCallback
+DeskRemovalAnimation::GetLatencyReportCallback() const {
+  return base::BindOnce([](const base::TimeDelta& latency) {
+    UMA_HISTOGRAM_TIMES(kDeskRemovalLatencyHistogramName, latency);
+  });
+}
+
+metrics_util::ReportCallback DeskRemovalAnimation::GetSmoothnessReportCallback()
+    const {
   return ash::metrics_util::ForSmoothness(
       base::BindRepeating([](int smoothness) {
         UMA_HISTOGRAM_PERCENTAGE(kDeskRemovalSmoothnessHistogramName,

ash/wm/desks/desk_animation_impl.h

@@ -37,7 +37,8 @@ class ASH_EXPORT DeskActivationAnimation : public DeskAnimationBase {
   bool EndSwipeAnimation() override;
   void OnStartingDeskScreenshotTakenInternal(int ending_desk_index) override;
   void OnDeskSwitchAnimationFinishedInternal() override;
-  metrics_util::ReportCallback GetReportCallback() const override;
+  LatencyReportCallback GetLatencyReportCallback() const override;
+  metrics_util::ReportCallback GetSmoothnessReportCallback() const override;
 
  private:
   FRIEND_TEST_ALL_PREFIXES(DeskActivationAnimationTest,
@@ -82,7 +83,8 @@ class DeskRemovalAnimation : public DeskAnimationBase {
   // DeskAnimationBase:
   void OnStartingDeskScreenshotTakenInternal(int ending_desk_index) override;
   void OnDeskSwitchAnimationFinishedInternal() override;
-  metrics_util::ReportCallback GetReportCallback() const override;
+  LatencyReportCallback GetLatencyReportCallback() const override;
+  metrics_util::ReportCallback GetSmoothnessReportCallback() const override;
 
  private:
   const int desk_to_remove_index_;

ash/wm/desks/desks_unittests.cc

@@ -1927,6 +1927,30 @@ TEST_F(DesksTest, FullscreenStateUpdatedAcrossDesks) {
   EXPECT_TRUE(full_screen_state_observer.is_fullscreen());
 }
 
+// Tests the Ash.Desks.AnimationLatency.DeskActivation histogram.
+TEST_F(DesksTest, AnimationLatencyDeskActivation) {
+  NewDesk();
+  auto* controller = DesksController::Get();
+  ASSERT_EQ(2u, controller->desks().size());
+
+  base::HistogramTester histogram_tester;
+  ActivateDesk(controller->desks()[1].get());
+  histogram_tester.ExpectTotalCount("Ash.Desks.AnimationLatency.DeskActivation",
+                                    1);
+}
+
+// Tests the Ash.Desks.AnimationLatency.DeskRemoval histogram.
+TEST_F(DesksTest, AnimationLatencyDeskRemoval) {
+  NewDesk();
+  auto* controller = DesksController::Get();
+  ASSERT_EQ(2u, controller->desks().size());
+
+  base::HistogramTester histogram_tester;
+  RemoveDesk(controller->desks()[0].get());
+  histogram_tester.ExpectTotalCount("Ash.Desks.AnimationLatency.DeskRemoval",
+                                    1);
+}
+
 class DesksWithMultiDisplayOverview : public AshTestBase {
  public:
   DesksWithMultiDisplayOverview() = default;

tools/metrics/histograms/metadata/ash/histograms.xml

@@ -1172,6 +1172,30 @@ chromium-metrics-reviews@google.com.
   </summary>
 </histogram>
 
+<histogram name="Ash.Desks.AnimationLatency.DeskActivation" units="ms"
+    expires_after="2023-04-23">
+  <owner>amusbach@chromium.org</owner>
+  <owner>afakhry@chromium.org</owner>
+  <owner>tclaiborne@chromium.org</owner>
+  <summary>
+    Emitted when the virtual desks activation animation begins, to report the
+    latency of starting this animation. In a continuous desk animation, this
+    metric is recorded only for the first desk switch.
+  </summary>
+</histogram>
+
+<histogram name="Ash.Desks.AnimationLatency.DeskRemoval" units="ms"
+    expires_after="2023-04-23">
+  <owner>amusbach@chromium.org</owner>
+  <owner>afakhry@chromium.org</owner>
+  <owner>tclaiborne@chromium.org</owner>
+  <summary>
+    Emitted when the virtual desks removal animation begins, to report the
+    latency of starting this animation. In a continuous desk animation, this
+    metric is recorded only for the first desk switch.
+  </summary>
+</histogram>
+
 <histogram name="Ash.Desks.AnimationSmoothness.DeskActivation" units="%"
     expires_after="2023-04-23">
   <owner>afakhry@chromium.org</owner>