Report the duration of sampled tasks with histogram.

components/scheduler/renderer/task_time_reporter.h

Index: components/scheduler/renderer/task_time_reporter.h
diff --git a/components/scheduler/renderer/task_time_reporter.h b/components/scheduler/renderer/task_time_reporter.h
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index 0000000000000000000000000000000000000000..d035f0ed41309c3480bf60041f64b17f5e806f7c
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+++ b/components/scheduler/renderer/task_time_reporter.h
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+// 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.
+
+#ifndef COMPONENTS_SCHEDULER_RENDERER_TASK_TIME_REPORTER_H_
+#define COMPONENTS_SCHEDULER_RENDERER_TASK_TIME_REPORTER_H_
+
+#include "base/time/time.h"
+#include "components/scheduler/scheduler_export.h"
+
+namespace scheduler {
+
+// Reports the task duration in a histogram for every 100th task. The histogram
+// ranges from 1 microsecond ~ 1 second with 100 bins. All tasks longer than 1
+// second will be put into the same bin.
+class SCHEDULER_EXPORT TaskTimeReporter {
+ public:
+  TaskTimeReporter();
+  ~TaskTimeReporter();
+  void ReportTaskTime(base::TimeDelta duration);
+
+ private:
+  int sample_count_;
+
+  DISALLOW_COPY_AND_ASSIGN(TaskTimeReporter);
+};
+}
+
+#endif  // COMPONENTS_SCHEDULER_RENDERER_TASK_TIME_REPORTER_H_