EQT: Record the max queueing time from navigation start to navigation away

third_party/WebKit/Source/platform/scheduler/renderer/renderer_scheduler_impl.cc

Index: third_party/WebKit/Source/platform/scheduler/renderer/renderer_scheduler_impl.cc
diff --git a/third_party/WebKit/Source/platform/scheduler/renderer/renderer_scheduler_impl.cc b/third_party/WebKit/Source/platform/scheduler/renderer/renderer_scheduler_impl.cc
index b3812dc5780262f6b79143108f71885aee99d4b6..377e68443fe2e6935d7ce1200c584c4015cd4a33 100644
--- a/third_party/WebKit/Source/platform/scheduler/renderer/renderer_scheduler_impl.cc
+++ b/third_party/WebKit/Source/platform/scheduler/renderer/renderer_scheduler_impl.cc
@@ -217,6 +217,7 @@ RendererSchedulerImpl::MainThreadOnly::MainThreadOnly(
       in_idle_period_for_testing(false),
       use_virtual_time(false),
       is_audio_playing(false),
+      during_navigation(false),
       rail_mode_observer(nullptr),
       wake_up_budget_pool(nullptr),
       task_duration_per_queue_type_histogram(base::Histogram::FactoryGet(
@@ -1635,6 +1636,7 @@ void RendererSchedulerImpl::OnNavigationStarted() {
   TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("renderer.scheduler"),
                "RendererSchedulerImpl::OnNavigationStarted");
   base::AutoLock lock(any_thread_lock_);
+  GetMainThreadOnly().during_navigation = true;
   ResetForNavigationLocked();
 }
 
@@ -1680,6 +1682,9 @@ void RendererSchedulerImpl::ResetForNavigationLocked() {
   GetMainThreadOnly().have_seen_a_begin_main_frame = false;
   GetMainThreadOnly().have_reported_blocking_intervention_since_navigation =
       false;
+  GetMainThreadOnly().max_queuing_time_histogram.reset();
+  GetMainThreadOnly().max_queuing_time = base::TimeDelta();
+
   for (WebViewSchedulerImpl* web_view_scheduler :
        GetMainThreadOnly().web_view_schedulers) {
     web_view_scheduler->OnNavigation();
@@ -1904,6 +1909,18 @@ void RendererSchedulerImpl::RemoveTaskTimeObserver(
 void RendererSchedulerImpl::OnQueueingTimeForWindowEstimated(
     base::TimeDelta queueing_time,
     base::TimeTicks window_start_time) {
+  if (GetMainThreadOnly().during_navigation) {
+    if (!GetMainThreadOnly().max_queuing_time_histogram) {

[tdresser, 2017/05/23 14:57:51]

Add a comment about why we're instantiating this here.

[Liquan (Max) Gu, 2017/05/25 16:27:28]

Done.

+      GetMainThreadOnly().max_queuing_time_histogram =
+          base::SingleSampleMetricsFactory::Get()->CreateCustomCountsMetric(
+              "RendererScheduler.MaxQueueingTime", 1, 10000, 50);
+    }
+    if (GetMainThreadOnly().max_queuing_time < queueing_time) {
+      GetMainThreadOnly().max_queuing_time_histogram->SetSample(
+          GetMainThreadOnly().max_queuing_time.InMilliseconds());
+      GetMainThreadOnly().max_queuing_time = queueing_time;
+    }
+  }
   // RendererScheduler reports the queueing time once per window's duration.
   //          |stepEQT|stepEQT|stepEQT|stepEQT|stepEQT|stepEQT|
   // Report:  |-------window EQT------|