Report expected task queueing time via UMA

components/scheduler/renderer/task_cost_estimator.cc

 // Copyright 2015 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/task_cost_estimator.h"
 
 #include "base/time/default_tick_clock.h"
 
 namespace scheduler {
 
@@ skipping 19 matching lines @@
     rolling_time_delta_history_.InsertSample(duration);
   }
 }
 
 base::TimeDelta TaskCostEstimator::expected_task_duration() const {
   return rolling_time_delta_history_.Percentile(estimation_percentile_);
 }
 
 void TaskCostEstimator::Clear() {
   rolling_time_delta_history_.Clear();
-  expected_task_duration_ = base::TimeDelta();
 }
 
 }  // namespace scheduler