Report expected task queueing time via UMA

components/scheduler/renderer/renderer_scheduler_impl.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 "components/scheduler/renderer/renderer_scheduler_impl.h"
 
 #include "base/bind.h"
 #include "base/debug/stack_trace.h"
 #include "base/logging.h"
+#include "base/metrics/histogram_macros.h"
 #include "base/trace_event/trace_event.h"
 #include "base/trace_event/trace_event_argument.h"
 #include "cc/output/begin_frame_args.h"
 #include "components/scheduler/base/task_queue_impl.h"
 #include "components/scheduler/base/task_queue_selector.h"
 #include "components/scheduler/base/virtual_time_domain.h"
 #include "components/scheduler/child/scheduler_tqm_delegate.h"
 #include "components/scheduler/renderer/web_view_scheduler_impl.h"
 #include "components/scheduler/renderer/webthread_impl_for_renderer_scheduler.h"
 
@@ skipping 18 matching lines @@
               TRACE_DISABLED_BY_DEFAULT("renderer.scheduler"),
               TRACE_DISABLED_BY_DEFAULT("renderer.scheduler.debug")),
       idle_helper_(&helper_,
                    this,
                    "renderer.scheduler",
                    TRACE_DISABLED_BY_DEFAULT("renderer.scheduler"),
                    "RendererSchedulerIdlePeriod",
                    base::TimeDelta()),
       render_widget_scheduler_signals_(this),
       control_task_runner_(helper_.ControlTaskRunner()),
-      compositor_task_runner_(
-          helper_.NewTaskQueue(TaskQueue::Spec("compositor_tq")
-                                   .SetShouldMonitorQuiescence(true))),
+      compositor_task_runner_(helper_.NewTaskQueue(
+          TaskQueue::Spec("compositor_tq").SetShouldMonitorQuiescence(true))),
       delayed_update_policy_runner_(
           base::Bind(&RendererSchedulerImpl::UpdatePolicy,
                      base::Unretained(this)),
           helper_.ControlTaskRunner()),
-      main_thread_only_(compositor_task_runner_,
+      main_thread_only_(this,
+                        compositor_task_runner_,
                         helper_.scheduler_tqm_delegate().get()),
       policy_may_need_update_(&any_thread_lock_),
       weak_factory_(this) {
   throttling_helper_.reset(new ThrottlingHelper(this, "renderer.scheduler"));
   update_policy_closure_ = base::Bind(&RendererSchedulerImpl::UpdatePolicy,
                                       weak_factory_.GetWeakPtr());
   end_renderer_hidden_idle_period_closure_.Reset(base::Bind(
       &RendererSchedulerImpl::EndIdlePeriod, weak_factory_.GetWeakPtr()));
 
   suspend_timers_when_backgrounded_closure_.Reset(
       base::Bind(&RendererSchedulerImpl::SuspendTimerQueueWhenBackgrounded,
                  weak_factory_.GetWeakPtr()));
 
   default_loading_task_runner_ = NewLoadingTaskRunner("default_loading_tq");
   default_timer_task_runner_ = NewTimerTaskRunner("default_timer_tq");
 
   TRACE_EVENT_OBJECT_CREATED_WITH_ID(
       TRACE_DISABLED_BY_DEFAULT("renderer.scheduler"), "RendererScheduler",
       this);
 
   helper_.SetObserver(this);
+  AddTaskObserver(&MainThreadOnly().queueing_time_estimator);

[Sami, 2016/04/20 09:51:27]

Please also remove this in the destructor.

[tdresser, 2016/04/20 15:13:33]

Whoops, thanks!

 }
 
 RendererSchedulerImpl::~RendererSchedulerImpl() {
   TRACE_EVENT_OBJECT_DELETED_WITH_ID(
       TRACE_DISABLED_BY_DEFAULT("renderer.scheduler"), "RendererScheduler",
       this);
 
   for (const scoped_refptr<TaskQueue>& loading_queue : loading_task_runners_) {
     loading_queue->RemoveTaskObserver(
         &MainThreadOnly().loading_task_cost_estimator);
   }
   for (const scoped_refptr<TaskQueue>& timer_queue : timer_task_runners_) {
     timer_queue->RemoveTaskObserver(
         &MainThreadOnly().timer_task_cost_estimator);
   }
 
   // Ensure the renderer scheduler was shut down explicitly, because otherwise
   // we could end up having stale pointers to the Blink heap which has been
   // terminated by this point.
   DCHECK(MainThreadOnly().was_shutdown);
 }
 
 RendererSchedulerImpl::MainThreadOnly::MainThreadOnly(
+    RendererSchedulerImpl* renderer_scheduler_impl,
     const scoped_refptr<TaskQueue>& compositor_task_runner,
     base::TickClock* time_source)
     : loading_task_cost_estimator(time_source,
                                   kLoadingTaskEstimationSampleCount,
                                   kLoadingTaskEstimationPercentile),
       timer_task_cost_estimator(time_source,
                                 kTimerTaskEstimationSampleCount,
                                 kTimerTaskEstimationPercentile),
       idle_time_estimator(compositor_task_runner,
                           time_source,
                           kShortIdlePeriodDurationSampleCount,
                           kShortIdlePeriodDurationPercentile),
+      queueing_time_estimator(renderer_scheduler_impl,
+                              time_source,
+                              base::TimeDelta::FromSeconds(5)),
       current_use_case(UseCase::NONE),
       timer_queue_suspend_count(0),
       navigation_task_expected_count(0),
       expensive_task_policy(ExpensiveTaskPolicy::RUN),
       renderer_hidden(false),
       renderer_backgrounded(false),
       timer_queue_suspension_when_backgrounded_enabled(false),
       timer_queue_suspended_when_backgrounded(false),
       was_shutdown(false),
       loading_tasks_seem_expensive(false),
@@ skipping 1121 matching lines @@
         return;
     }
     MainThreadOnly().have_reported_blocking_intervention_since_navigation =
         true;
     BroadcastConsoleWarning(
         "Deferred long-running timer task(s) to improve scrolling smoothness. "
         "See crbug.com/574343.");
   }
 }
 
+void RendererSchedulerImpl::OnQueueingTimeForWindowEstimated(
+    base::TimeDelta queueing_time) {
+  UMA_HISTOGRAM_TIMES("RendererScheduler.ExpectedTaskQueueingDuration",

[Sami, 2016/04/20 09:51:27]

Would you mind adding a trace counter[1] for this estimate to see how it behaves
over time?

[1] See TRACE_COUNTER elsewhere in this file.

[tdresser, 2016/04/20 15:13:33]

Done.

+                      queueing_time);
+}
+
 }  // namespace scheduler