ash: Record latency for tab dragging in clamshell

Add histograms for tab dragging in clamshell mode.

Bug: 1032766
Change-Id: I33b9a39598ff06aa2c343a86e5e2effa79523d46
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2199501
Commit-Queue: Yichen Zhou <yichenz@chromium.org>
Reviewed-by: Ilya Sherman <isherman@chromium.org>
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Reviewed-by: Xiaoqian Dai <xdai@chromium.org>
Cr-Commit-Position: refs/heads/master@{#769943}

ash/wm/workspace/workspace_window_resizer.cc

@@ -75,6 +75,15 @@ constexpr int kMinOnscreenSize = 20;
 // snapped window before the window restores.
 constexpr int kResizeRestoreDragThresholdDp = 5;
 
+// The UMA histogram that records presentation time for tab dragging between
+// windows in clamshell mode.
+constexpr char kTabDraggingInClamshellModeHistogram[] =
+    "Ash.WorkspaceWindowResizer.TabDragging.PresentationTime.ClamshellMode";
+
+constexpr char kTabDraggingInClamshellModeMaxLatencyHistogram[] =
+    "Ash.WorkspaceWindowResizer.TabDragging.PresentationTime.MaxLatency."
+    "ClamshellMode";
+
 // Current instance for use by the WorkspaceWindowResizerTest.
 WorkspaceWindowResizer* instance = nullptr;
 
@@ -548,6 +557,20 @@ void WorkspaceWindowResizer::Drag(const gfx::PointF& location_in_parent,
         SnapType::kMaximize;
   }
   UpdateSnapPhantomWindow(location_in_screen, bounds);
+
+  if (tab_dragging_recorder_) {
+    // The recorder only works with a single ui::Compositor. ui::Compositor is
+    // per display so the recorder does not work correctly across different
+    // displays. Thus, we give up tab dragging latency data collection if the
+    // drag touches a different display, i.e. not inside the current parent's
+    // bounds.
+    if (!gfx::Rect(GetTarget()->parent()->bounds().size())
+             .Contains(gfx::ToRoundedPoint(location_in_parent))) {
+      tab_dragging_recorder_.reset();
+      return;
+    }
+    tab_dragging_recorder_->RequestNext();
+  }
 }
 
 void WorkspaceWindowResizer::CompleteDrag() {
@@ -618,10 +641,10 @@ void WorkspaceWindowResizer::CompleteDrag() {
     return;
   }
 
-    // Keep the window snapped if the user resizes the window such that the
-    // window has valid bounds for a snapped window. Always unsnap the window
-    // if the user dragged the window via the caption area because doing this
-    // is slightly less confusing.
+  // Keep the window snapped if the user resizes the window such that the
+  // window has valid bounds for a snapped window. Always unsnap the window
+  // if the user dragged the window via the caption area because doing this
+  // is slightly less confusing.
   if (window_state()->IsSnapped()) {
     if (details().window_component == HTCAPTION ||
         !AreBoundsValidSnappedBounds(window_state()->GetStateType(),
@@ -788,6 +811,13 @@ WorkspaceWindowResizer::WorkspaceWindowResizer(
 
   window_state->OnDragStarted(details().window_component);
   StartDragForAttachedWindows();
+
+  if (window_util::IsDraggingTabs(window_state->window())) {
+    tab_dragging_recorder_ = CreatePresentationTimeHistogramRecorder(
+        GetTarget()->layer()->GetCompositor(),
+        kTabDraggingInClamshellModeHistogram,
+        kTabDraggingInClamshellModeMaxLatencyHistogram);
+  }
 }
 
 void WorkspaceWindowResizer::LayoutAttachedWindows(gfx::Rect* bounds) {

ash/wm/workspace/workspace_window_resizer.h

@@ -217,6 +217,9 @@ class ASH_EXPORT WorkspaceWindowResizer : public WindowResizer {
   // be set to the bounds of the window when the drag was started.
   gfx::Rect pre_drag_window_bounds_;
 
+  // Presentation time recorder for tab dragging in clamshell mode.
+  std::unique_ptr<PresentationTimeRecorder> tab_dragging_recorder_;
+
   // Used to determine if this has been deleted during a drag such as when a tab
   // gets dragged into another browser window.
   base::WeakPtrFactory<WorkspaceWindowResizer> weak_ptr_factory_{this};

ash/wm/workspace/workspace_window_resizer_unittest.cc

@@ -5,6 +5,7 @@
 #include "ash/wm/workspace/workspace_window_resizer.h"
 
 #include "ash/public/cpp/shell_window_ids.h"
+#include "ash/public/cpp/window_properties.h"
 #include "ash/screen_util.h"
 #include "ash/shelf/shelf.h"
 #include "ash/shell.h"
@@ -2088,4 +2089,52 @@ TEST_F(MultiDisplayWorkspaceWindowResizerTest, Magnetism) {
   EXPECT_EQ(gfx::Rect(1150, 10, 100, 100), win1->GetBoundsInScreen());
 }
 
+// Make sure metrics is recorded during tab dragging.
+TEST_F(WorkspaceWindowResizerTest, TabDraggingHistogram) {
+  UpdateDisplay("800x600,800x600");
+  ASSERT_EQ(2, display::Screen::GetScreen()->GetNumDisplays());
+
+  struct {
+    bool is_dragging_tab;
+    gfx::PointF drag_to_point;
+    int expected_latency_count;
+    int expected_max_latency_count;
+  } kTestCases[] = {// A tab dragging should generate a histogram.
+                    {/*is_dragging_tab*/ true, gfx::PointF(200, 200), 1, 1},
+                    // A window dragging should not generate a histogram.
+                    {/*is_dragging_tab*/ false, gfx::PointF(200, 200), 0, 0},
+                    // A tab dragging should not generate a histogram when
+                    // the drag touches a different display.
+                    {/*is_dragging_tab*/ true, gfx::PointF(850, 200), 0, 0}};
+
+  for (const auto& test : kTestCases) {
+    SCOPED_TRACE(testing::Message()
+                 << "is_dragging_tab=" << test.is_dragging_tab);
+
+    base::HistogramTester histogram_tester;
+    window_->SetBounds(gfx::Rect(100, 100, 100, 100));
+    window_->SetProperty(ash::kIsDraggingTabsKey, test.is_dragging_tab);
+
+    std::unique_ptr<WindowResizer> resizer =
+        CreateWindowResizer(window_.get(), gfx::PointF(), HTCAPTION,
+                            ::wm::WINDOW_MOVE_SOURCE_MOUSE);
+    ASSERT_TRUE(resizer.get());
+    resizer->Drag(test.drag_to_point, 0);
+
+    EXPECT_TRUE(
+        ui::WaitForNextFrameToBePresented(window_->GetHost()->compositor()));
+
+    resizer->CompleteDrag();
+    resizer.reset(nullptr);
+
+    histogram_tester.ExpectTotalCount(
+        "Ash.WorkspaceWindowResizer.TabDragging.PresentationTime.ClamshellMode",
+        test.expected_latency_count);
+    histogram_tester.ExpectTotalCount(
+        "Ash.WorkspaceWindowResizer.TabDragging.PresentationTime.MaxLatency."
+        "ClamshellMode",
+        test.expected_max_latency_count);
+  }
+}
+
 }  // namespace ash

tools/metrics/histograms/histograms.xml

@@ -10927,6 +10927,28 @@ reviews. Googlers can read more about this at go/gwsq-gerrit.
   </summary>
 </histogram>
 
+<histogram
+    name="Ash.WorkspaceWindowResizer.TabDragging.PresentationTime.ClamshellMode"
+    units="ms" expires_after="2021-02-03">
+  <owner>yichenz@chromium.org</owner>
+  <owner>chromeos-wmp@google.com</owner>
+  <summary>
+    Presentation time in ms when a tab is dragged in clamshell mode. Each time
+    the tab is dragged within a display, the time it takes to present the new
+    frame on screen is recorded.
+  </summary>
+</histogram>
+
+<histogram
+    name="Ash.WorkspaceWindowResizer.TabDragging.PresentationTime.MaxLatency.ClamshellMode"
+    units="ms" expires_after="2021-02-03">
+  <owner>yichenz@chromium.org</owner>
+  <owner>chromeos-wmp@google.com</owner>
+  <summary>
+    Maximum presentation time recorded during the tab dragging session.
+  </summary>
+</histogram>
+
 <histogram name="Assistant.ButtonClickCount" enum="AssistantButtonId"
     expires_after="2020-10-25">
   <owner>xiaohuic@chromium.org</owner>