Report the duration of sampled tasks with histogram.

components/scheduler/renderer/task_time_reporter_unittest.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/renderer/task_time_reporter.h"
+
+#include "base/test/histogram_tester.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace scheduler {
+TEST(TaskTimeReporterTest, LoggingTime) {
+  base::HistogramTester tester;
+
+  TaskTimeReporter task_time_reporter;
+  task_time_reporter.ReportTaskTime(base::TimeDelta::FromMicroseconds(1));
+  task_time_reporter.ReportTaskTime(base::TimeDelta::FromMilliseconds(1));
+  task_time_reporter.ReportTaskTime(base::TimeDelta::FromMilliseconds(10));
+  task_time_reporter.ReportTaskTime(base::TimeDelta::FromSeconds(1));
+  task_time_reporter.ReportTaskTime(base::TimeDelta::FromSeconds(2));
+  tester.ExpectBucketCount("RendererScheduler.TaskTime", 1, 1);
+  tester.ExpectBucketCount("RendererScheduler.TaskTime", 1000, 1);
+  tester.ExpectBucketCount("RendererScheduler.TaskTime", 10000, 1);
+  tester.ExpectBucketCount("RendererScheduler.TaskTime", 1000000, 2);
+  tester.ExpectTotalCount("RendererScheduler.TaskTime", 5);
+}
+}