Create Ukm ReportingService implementation.

components/ukm/ukm_rotation_scheduler.h

+// Copyright 2017 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_UKM_METRICS_REPORTING_SCHEDULER_H_
+#define COMPONENTS_UKM_METRICS_REPORTING_SCHEDULER_H_
+
+#include "base/time/time.h"
+#include "components/metrics/metrics_rotation_scheduler.h"
+
+namespace ukm {
+
+// Scheduler to drive a UkmService object's log rotations.
+class UkmRotationScheduler : public metrics::MetricsRotationScheduler {
+ public:
+  // Creates UkmRotationScheduler object with the given |rotation_callback|
+  // callback to call when log rotation should happen and |interval_callback|
+  // to determine the interval between rotations in steady state.
+  UkmRotationScheduler(
+      const base::Closure& rotation_callback,
+      const base::Callback<base::TimeDelta(void)>& interval_callback);
+  ~UkmRotationScheduler() override;
+
+ private:
+  // Record the init sequence order histogram.
+  void LogMetricsInitSequence(InitSequence sequence) override;
+
+  DISALLOW_COPY_AND_ASSIGN(UkmRotationScheduler);
+};
+
+}  // namespace ukm
+
+#endif  // COMPONENTS_UKM_METRICS_REPORTING_SCHEDULER_H_