Add sub-metrics for Event.Latency.TouchToFirstScrollUpdateSwapBegin

content/browser/renderer_host/input/render_widget_host_latency_tracker.cc

 // Copyright 2014 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 "content/browser/renderer_host/input/render_widget_host_latency_tracker.h"
 
 #include <stddef.h>
 
 #include "base/logging.h"
 #include "base/metrics/histogram.h"
@@ skipping 109 matching lines @@
     // SpeculativeLaunchServiceWorker experimentation. So remove this UMA when
     // the experimentation finished (crbug.com/638827).
     if (is_running_navigation_hint_task) {
       for (size_t i = 0; i < original_component.event_count; i++) {
         UMA_HISTOGRAM_TOUCH_TO_SCROLL_LATENCY(
             "Event.Latency.TouchToFirstScrollUpdateSwapBegin_"
             "IsRunningNavigationHintTask",
             original_component, gpu_swap_begin_component);
       }
     }
+
+    // TODO(miletus): Add validation for making sure the following components
+    // are present and their event times are legit.

[tdresser, 2016/08/23 13:57:00]

miletus doesn't work here anymore. 
I assume this is just copied?

We can probably just get rid of this TODO.

[lanwei, 2016/08/24 03:08:28]

Done.

+    LatencyInfo::LatencyComponent rendering_scheduled_component;
+    bool rendering_scheduled_on_main = latency.FindLatency(
+        ui::INPUT_EVENT_LATENCY_RENDERING_SCHEDULED_MAIN_COMPONENT, 0,
+        &rendering_scheduled_component);
+
+    if (!rendering_scheduled_on_main) {
+      if (!latency.FindLatency(
+              ui::INPUT_EVENT_LATENCY_RENDERING_SCHEDULED_IMPL_COMPONENT, 0,
+              &rendering_scheduled_component))
+        goto allScrollUpdate;

[tdresser, 2016/08/23 13:57:00]

Rewrite without using goto.

It's barely mentioned in the style guide, but it's called out as "vanishingly
rare", which is enough to not want to use it.

You could refactor these into a method that returns when a component isn't
found?

[lanwei, 2016/08/24 03:08:28]

Done.

+    }
+
+    if (rendering_scheduled_on_main) {
+      UMA_HISTOGRAM_SCROLL_LATENCY_LONG(
+          "Event.Latency.FirstScrollUpdate.FirstTouchToHandled_Main",
+          original_component, rendering_scheduled_component);
+    } else {
+      UMA_HISTOGRAM_SCROLL_LATENCY_LONG(
+          "Event.Latency.FirstScrollUpdate.FirstTouchToHandled_Impl",
+          original_component, rendering_scheduled_component);
+    }
+
+    LatencyInfo::LatencyComponent renderer_swap_component;
+    if (!latency.FindLatency(ui::INPUT_EVENT_LATENCY_RENDERER_SWAP_COMPONENT, 0,
+                             &renderer_swap_component))
+      goto allScrollUpdate;
+
+    if (rendering_scheduled_on_main) {
+      UMA_HISTOGRAM_SCROLL_LATENCY_LONG(
+          "Event.Latency.FirstScrollUpdate.HandledToRendererSwap_Main",
+          rendering_scheduled_component, renderer_swap_component);
+    } else {
+      UMA_HISTOGRAM_SCROLL_LATENCY_LONG(
+          "Event.Latency.FirstScrollUpdate.HandledToRendererSwap_Impl",
+          rendering_scheduled_component, renderer_swap_component);
+    }
+
+    LatencyInfo::LatencyComponent browser_received_swap_component;
+    if (!latency.FindLatency(
+            ui::INPUT_EVENT_BROWSER_RECEIVED_RENDERER_SWAP_COMPONENT, 0,
+            &browser_received_swap_component))
+      goto allScrollUpdate;
+
+    UMA_HISTOGRAM_SCROLL_LATENCY_SHORT(
+        "Event.Latency.FirstScrollUpdate.RendererSwapToBrowserNotified",
+        renderer_swap_component, browser_received_swap_component);
+
+    UMA_HISTOGRAM_SCROLL_LATENCY_LONG(
+        "Event.Latency.FirstScrollUpdate.BrowserNotifiedToBeforeGpuSwap",
+        browser_received_swap_component, gpu_swap_begin_component);
+
+    UMA_HISTOGRAM_SCROLL_LATENCY_SHORT(
+        "Event.Latency.FirstScrollUpdate.GpuSwap", gpu_swap_begin_component,
+        gpu_swap_end_component);
   } else if (!latency.FindLatency(
                  ui::INPUT_EVENT_LATENCY_SCROLL_UPDATE_ORIGINAL_COMPONENT,
                  latency_component_id, &original_component)) {
     return;
   }
 
+allScrollUpdate:
   // This UMA metric tracks the time from when the original touch event is
   // created to when the scroll gesture results in final frame swap.
   for (size_t i = 0; i < original_component.event_count; i++) {
     UMA_HISTOGRAM_TOUCH_TO_SCROLL_LATENCY(
         "Event.Latency.TouchToScrollUpdateSwapBegin", original_component,
         gpu_swap_begin_component);
   }
   // TODO(horo): IsRunningNavigationHintTask UMAs are only for
   // SpeculativeLaunchServiceWorker experimentation. So remove this UMA when
   // the experimentation finished (crbug.com/638827).
   if (is_running_navigation_hint_task) {
     for (size_t i = 0; i < original_component.event_count; i++) {
       UMA_HISTOGRAM_TOUCH_TO_SCROLL_LATENCY(
           "Event.Latency.TouchToScrollUpdateSwapBegin_"
           "IsRunningNavigationHintTask",
           original_component, gpu_swap_begin_component);
     }
   }
 
   // TODO(miletus): Add validation for making sure the following components
   // are present and their event times are legit.
   LatencyInfo::LatencyComponent rendering_scheduled_component;
   bool rendering_scheduled_on_main = latency.FindLatency(
       ui::INPUT_EVENT_LATENCY_RENDERING_SCHEDULED_MAIN_COMPONENT,
       0, &rendering_scheduled_component);
-
   if (!rendering_scheduled_on_main) {
     if (!latency.FindLatency(
             ui::INPUT_EVENT_LATENCY_RENDERING_SCHEDULED_IMPL_COMPONENT,
             0, &rendering_scheduled_component))
       return;
   }
 
   if (rendering_scheduled_on_main) {
     UMA_HISTOGRAM_SCROLL_LATENCY_LONG(
         "Event.Latency.ScrollUpdate.TouchToHandled_Main",
@@ skipping 421 matching lines @@
                            latency_component_id_, nullptr)) {
     return;
   }
 
   ComputeScrollLatencyHistograms(gpu_swap_begin_component,
                                  gpu_swap_end_component, latency_component_id_,
                                  latency, is_running_navigation_hint_task);
 }
 
 }  // namespace content