Basic UkmService implementation

components/ukm/persisted_logs_metrics_impl.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_PERSISTED_LOGS_METRICS_IMPL_H_
+#define COMPONENTS_UKM_PERSISTED_LOGS_METRICS_IMPL_H_
+
+#include "base/macros.h"
+#include "components/metrics/persisted_logs_metrics.h"
+
+namespace ukm {
+
+// Implementation for recording metrics from PersistedLogs.
+class PersistedLogsMetricsImpl : public metrics::PersistedLogsMetrics {
+ public:
+  PersistedLogsMetricsImpl() {}
+  ~PersistedLogsMetricsImpl() {}

[Alexei Svitkine (slow), 2017/01/10 17:37:19]

override

and the base class's dtor should be marked virtual

[Steven Holte, 2017/01/10 22:52:44]

Done.

+
+  metrics::PersistedLogs::LogReadStatus RecordLogReadStatus(
+      metrics::PersistedLogs::LogReadStatus status) override;
+

[Alexei Svitkine (slow), 2017/01/10 17:37:19]

Nit: No need for blank lines between override methods. Also put //
metrics::PersistedLogsMetrics: above them all.

[Steven Holte, 2017/01/10 22:52:44]

Done.

+  void RecordCompressionRatio(size_t compressed_size,
+                              size_t original_size) override;
+
+  void RecordDroppedLogSize(size_t size) override;
+
+  void RecordDroppedLogsNum(int dropped_logs_num) override;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(PersistedLogsMetricsImpl);
+};
+
+}  // namespace ukm
+
+#endif  // COMPONENTS_UKM_PERSISTED_LOGS_METRICS_IMPL_H_