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
new file mode 100644
index 0000000000000000000000000000000000000000..0efaa8f674027a81a7c8407a24000cfdef903d7c
--- /dev/null
+++ b/components/scheduler/renderer/task_time_reporter.h
@@ -0,0 +1,26 @@
+// 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 each task duration in a histogram. The histogram ranges from 1
+// microsecond ~ 1 second with 50 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);
+
+  DISALLOW_COPY_AND_ASSIGN(TaskTimeReporter);
+};
+}
+
+#endif  // COMPONENTS_SCHEDULER_RENDERER_TASK_TIME_REPORTER_H_