Report expected task queueing time via UMA

components/scheduler/base/task_time_tracker.cc

+// Copyright 2016 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/base/task_time_tracker.h"
+
+#include "base/trace_event/trace_event.h"
+
+namespace scheduler {
+
+TaskTimeTracker::TaskTimeTracker(TaskTimeTracker::Observer* observer)
+    : observer_(observer) {}
+
+TaskTimeTracker::~TaskTimeTracker() {}
+
+void TaskTimeTracker::ReportTaskTime(base::TimeTicks task_start_time,
+                                     base::TimeTicks task_end_time) {
+  if (observer_)
+    observer_->ReportTaskTime(task_start_time, task_end_time);
+}
+
+} // scheduler