Basic UkmService implementation

components/ukm/metrics_reporting_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_reporting_scheduler.h"
+
+namespace ukm {
+
+// Scheduler task to drive a MetricsService object's uploading.
+class MetricsReportingScheduler : public metrics::MetricsReportingScheduler {
+ public:
+  // Creates MetricsServiceScheduler object with the given |upload_callback|
+  // callback to call when uploading should happen and
+  // |upload_interval_callback| to determine the interval between uploads
+  // in steady state.
+  MetricsReportingScheduler(
+      const base::Closure& upload_callback,
+      const base::Callback<base::TimeDelta(void)>& upload_interval_callback);
+  ~MetricsReportingScheduler() override;
+
+ private:
+  // Record the init sequence order histogram.
+  void LogMetricsInitSequence(InitSequence sequence) override;
+
+  // Record the upload interval time.
+  void LogActualUploadInterval(base::TimeDelta interval) override;
+
+  DISALLOW_COPY_AND_ASSIGN(MetricsReportingScheduler);
+};
+
+}  // namespace ukm
+
+#endif  // COMPONENTS_UKM_METRICS_REPORTING_SCHEDULER_H_