latency: Remove another unnecessary component.

The INPUT_EVENT_LATENCY_ACK_RWH_COMPONENT component is set from the
browser, and immediately looked up in the same cycle. So remove the
component, and use the timestamp directly instead.

BUG=849719

Change-Id: Id28352d7ad0f56c5b0b89df26c9aa45d3d190f55
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2093019
Commit-Queue: Ken Buchanan <kenrb@chromium.org>
Auto-Submit: Sadrul Chowdhury <sadrul@chromium.org>
Reviewed-by: Ken Buchanan <kenrb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#748271}

content/browser/renderer_host/input/render_widget_host_latency_tracker.cc

@@ -91,7 +91,9 @@ RenderWidgetHostLatencyTracker::~RenderWidgetHostLatencyTracker() {}
 void RenderWidgetHostLatencyTracker::ComputeInputLatencyHistograms(
     WebInputEvent::Type type,
     const LatencyInfo& latency,
-    InputEventAckState ack_result) {
+    InputEventAckState ack_result,
+    base::TimeTicks ack_timestamp) {
+  DCHECK(!ack_timestamp.is_null());
   // If this event was coalesced into another event, ignore it, as the event it
   // was coalesced into will reflect the full latency.
   if (latency.coalesced())
@@ -144,14 +146,10 @@ void RenderWidgetHostLatencyTracker::ComputeInputLatencyHistograms(
     }
   }
 
-  base::TimeTicks rwh_ack_timestamp;
-  if (latency.FindLatency(ui::INPUT_EVENT_LATENCY_ACK_RWH_COMPONENT,
-                          &rwh_ack_timestamp)) {
-    if (!multi_finger_touch_gesture && !main_thread_timestamp.is_null()) {
-      UMA_HISTOGRAM_INPUT_LATENCY_MILLISECONDS(
-          "Event.Latency.BlockingTime." + event_name + default_action_status,
-          main_thread_timestamp, rwh_ack_timestamp);
-    }
+  if (!multi_finger_touch_gesture && !main_thread_timestamp.is_null()) {
+    UMA_HISTOGRAM_INPUT_LATENCY_MILLISECONDS(
+        "Event.Latency.BlockingTime." + event_name + default_action_status,
+        main_thread_timestamp, ack_timestamp);
   }
 }
 
@@ -252,7 +250,6 @@ void RenderWidgetHostLatencyTracker::OnInputEventAck(
     }
   }
 
-  latency->AddLatencyNumber(ui::INPUT_EVENT_LATENCY_ACK_RWH_COMPONENT);
   // If this event couldn't have caused a gesture event, and it didn't trigger
   // rendering, we're done processing it. If the event got coalesced then
   // terminate it as well. We also exclude cases where we're against the scroll
@@ -263,7 +260,8 @@ void RenderWidgetHostLatencyTracker::OnInputEventAck(
     latency->Terminate();
   }
 
-  ComputeInputLatencyHistograms(event.GetType(), *latency, ack_result);
+  ComputeInputLatencyHistograms(event.GetType(), *latency, ack_result,
+                                base::TimeTicks::Now());
 }
 
 void RenderWidgetHostLatencyTracker::OnEventStart(ui::LatencyInfo* latency) {

content/browser/renderer_host/input/render_widget_host_latency_tracker.h

@@ -29,7 +29,8 @@ class CONTENT_EXPORT RenderWidgetHostLatencyTracker {
 
   void ComputeInputLatencyHistograms(blink::WebInputEvent::Type type,
                                      const ui::LatencyInfo& latency,
-                                     InputEventAckState ack_result);
+                                     InputEventAckState ack_result,
+                                     base::TimeTicks ack_timestamp);
 
   // Populates the LatencyInfo with relevant entries for latency tracking.
   // Called when an event is received by the RenderWidgetHost, prior to

content/browser/renderer_host/input/render_widget_host_latency_tracker_unittest.cc

@@ -972,18 +972,15 @@ TEST_F(RenderWidgetHostLatencyTrackerTest, TouchBlockingAndQueueingTime) {
           base::TimeTicks() +
               base::TimeDelta::FromMilliseconds(touchstart_timestamps_ms[1]));
 
-      fake_latency.AddLatencyNumberWithTimestamp(
-          ui::INPUT_EVENT_LATENCY_ACK_RWH_COMPONENT,
+      auto ack_timestamp =
           base::TimeTicks() +
-              base::TimeDelta::FromMilliseconds(touchstart_timestamps_ms[2]));
+          base::TimeDelta::FromMilliseconds(touchstart_timestamps_ms[2]);
 
       // Call ComputeInputLatencyHistograms directly to avoid OnInputEventAck
       // overwriting components.
       tracker()->ComputeInputLatencyHistograms(event.GetType(), fake_latency,
-                                               blocking);
-
-      tracker()->OnInputEventAck(event, &latency,
-                                 blocking);
+                                               blocking, ack_timestamp);
+      tracker()->OnInputEventAck(event, &latency, blocking);
     }
 
     {
@@ -1013,15 +1010,14 @@ TEST_F(RenderWidgetHostLatencyTrackerTest, TouchBlockingAndQueueingTime) {
           base::TimeTicks() +
               base::TimeDelta::FromMilliseconds(touchmove_timestamps_ms[1]));
 
-      fake_latency.AddLatencyNumberWithTimestamp(
-          ui::INPUT_EVENT_LATENCY_ACK_RWH_COMPONENT,
+      auto ack_timestamp =
           base::TimeTicks() +
-              base::TimeDelta::FromMilliseconds(touchmove_timestamps_ms[2]));
+          base::TimeDelta::FromMilliseconds(touchmove_timestamps_ms[2]);
 
       // Call ComputeInputLatencyHistograms directly to avoid OnInputEventAck
       // overwriting components.
       tracker()->ComputeInputLatencyHistograms(event.GetType(), fake_latency,
-                                               blocking);
+                                               blocking, ack_timestamp);
     }
 
     {
@@ -1051,15 +1047,14 @@ TEST_F(RenderWidgetHostLatencyTrackerTest, TouchBlockingAndQueueingTime) {
           base::TimeTicks() +
               base::TimeDelta::FromMilliseconds(touchend_timestamps_ms[1]));
 
-      fake_latency.AddLatencyNumberWithTimestamp(
-          ui::INPUT_EVENT_LATENCY_ACK_RWH_COMPONENT,
+      auto ack_timestamp =
           base::TimeTicks() +
-              base::TimeDelta::FromMilliseconds(touchend_timestamps_ms[2]));
+          base::TimeDelta::FromMilliseconds(touchend_timestamps_ms[2]);
 
       // Call ComputeInputLatencyHistograms directly to avoid OnInputEventAck
       // overwriting components.
       tracker()->ComputeInputLatencyHistograms(event.GetType(), fake_latency,
-                                               blocking);
+                                               blocking, ack_timestamp);
     }
   }
 
@@ -1149,15 +1144,14 @@ TEST_F(RenderWidgetHostLatencyTrackerTest, KeyBlockingAndQueueingTime) {
           base::TimeTicks() +
               base::TimeDelta::FromMilliseconds(event_timestamps_ms[1]));
 
-      fake_latency.AddLatencyNumberWithTimestamp(
-          ui::INPUT_EVENT_LATENCY_ACK_RWH_COMPONENT,
+      auto ack_timestamp =
           base::TimeTicks() +
-              base::TimeDelta::FromMilliseconds(event_timestamps_ms[2]));
+          base::TimeDelta::FromMilliseconds(event_timestamps_ms[2]);
 
       // Call ComputeInputLatencyHistograms directly to avoid OnInputEventAck
       // overwriting components.
       tracker()->ComputeInputLatencyHistograms(event.GetType(), fake_latency,
-                                               blocking);
+                                               blocking, ack_timestamp);
 
       tracker()->OnInputEventAck(event, &latency_info, blocking);
     }
@@ -1252,15 +1246,13 @@ TEST_F(RenderWidgetHostLatencyTrackerTest,
         base::TimeTicks() +
             base::TimeDelta::FromMilliseconds(touchstart_timestamps_ms[1]));
 
-    fake_latency.AddLatencyNumberWithTimestamp(
-        ui::INPUT_EVENT_LATENCY_ACK_RWH_COMPONENT,
-        base::TimeTicks() +
-            base::TimeDelta::FromMilliseconds(touchstart_timestamps_ms[2]));
+    auto ack_timestamp = base::TimeTicks() + base::TimeDelta::FromMilliseconds(
+                                                 touchstart_timestamps_ms[2]);
 
     // Call ComputeInputLatencyHistograms directly to avoid OnInputEventAck
     // overwriting components.
-    tracker()->ComputeInputLatencyHistograms(event.GetType(),
-                                             fake_latency, ack_state);
+    tracker()->ComputeInputLatencyHistograms(event.GetType(), fake_latency,
+                                             ack_state, ack_timestamp);
 
     tracker()->OnInputEventAck(event, &latency, ack_state);
   }

ui/latency/latency_info.cc

@@ -36,7 +36,6 @@ const char* GetComponentName(ui::LatencyComponentType type) {
     CASE_TYPE(INPUT_EVENT_LATENCY_RENDERING_SCHEDULED_MAIN_COMPONENT);
     CASE_TYPE(INPUT_EVENT_LATENCY_RENDERING_SCHEDULED_IMPL_COMPONENT);
     CASE_TYPE(INPUT_EVENT_LATENCY_SCROLL_UPDATE_LAST_EVENT_COMPONENT);
-    CASE_TYPE(INPUT_EVENT_LATENCY_ACK_RWH_COMPONENT);
     CASE_TYPE(INPUT_EVENT_LATENCY_RENDERER_MAIN_COMPONENT);
     CASE_TYPE(INPUT_EVENT_LATENCY_RENDERER_SWAP_COMPONENT);
     CASE_TYPE(DISPLAY_COMPOSITOR_RECEIVED_FRAME_COMPONENT);

ui/latency/latency_info.h

@@ -65,8 +65,6 @@ enum LatencyComponentType {
   INPUT_EVENT_LATENCY_RENDERING_SCHEDULED_IMPL_COMPONENT,
   // Original timestamp of the last event that has been coalesced into this one.
   INPUT_EVENT_LATENCY_SCROLL_UPDATE_LAST_EVENT_COMPONENT,
-  // Timestamp when the event's ack is received by the RWH.
-  INPUT_EVENT_LATENCY_ACK_RWH_COMPONENT,
   // Timestamp when the frame is swapped in renderer.
   INPUT_EVENT_LATENCY_RENDERER_SWAP_COMPONENT,
   // Timestamp of when the display compositor receives a compositor frame from

ui/latency/mojom/latency_info.mojom

@@ -31,8 +31,6 @@ enum LatencyComponentType {
   INPUT_EVENT_LATENCY_RENDERING_SCHEDULED_IMPL_COMPONENT,
   // Timestamp for last event that has been coalesced into this one.
   INPUT_EVENT_LATENCY_SCROLL_UPDATE_LAST_EVENT_COMPONENT,
-  // Timestamp when the event's ack is received by the RWH.
-  INPUT_EVENT_LATENCY_ACK_RWH_COMPONENT,
   // Timestamp when the frame is swapped in renderer.
   INPUT_EVENT_LATENCY_RENDERER_SWAP_COMPONENT,
   // Timestamp of when the display compositor receives a compositor frame.

ui/latency/mojom/latency_info_mojom_traits.cc

@@ -169,9 +169,6 @@ EnumTraits<ui::mojom::LatencyComponentType, ui::LatencyComponentType>::ToMojom(
     case ui::INPUT_EVENT_LATENCY_SCROLL_UPDATE_LAST_EVENT_COMPONENT:
       return ui::mojom::LatencyComponentType::
           INPUT_EVENT_LATENCY_SCROLL_UPDATE_LAST_EVENT_COMPONENT;
-    case ui::INPUT_EVENT_LATENCY_ACK_RWH_COMPONENT:
-      return ui::mojom::LatencyComponentType::
-          INPUT_EVENT_LATENCY_ACK_RWH_COMPONENT;
     case ui::INPUT_EVENT_LATENCY_RENDERER_SWAP_COMPONENT:
       return ui::mojom::LatencyComponentType::
           INPUT_EVENT_LATENCY_RENDERER_SWAP_COMPONENT;
@@ -225,9 +222,6 @@ bool EnumTraits<ui::mojom::LatencyComponentType, ui::LatencyComponentType>::
         INPUT_EVENT_LATENCY_RENDERING_SCHEDULED_IMPL_COMPONENT:
       *output = ui::INPUT_EVENT_LATENCY_RENDERING_SCHEDULED_IMPL_COMPONENT;
       return true;
-    case ui::mojom::LatencyComponentType::INPUT_EVENT_LATENCY_ACK_RWH_COMPONENT:
-      *output = ui::INPUT_EVENT_LATENCY_ACK_RWH_COMPONENT;
-      return true;
     case ui::mojom::LatencyComponentType::
         INPUT_EVENT_LATENCY_RENDERER_SWAP_COMPONENT:
       *output = ui::INPUT_EVENT_LATENCY_RENDERER_SWAP_COMPONENT;