Delegate PersistedLogs metrics recording

components/metrics/persisted_logs_metrics.h

Index: components/metrics/persisted_logs_metrics.h
diff --git a/components/metrics/persisted_logs_metrics.h b/components/metrics/persisted_logs_metrics.h
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+++ b/components/metrics/persisted_logs_metrics.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_METRICS_PERSISTED_LOGS_METRICS_H_
+#define COMPONENTS_METRICS_PERSISTED_LOGS_METRICS_H_
+
+#include "base/macros.h"
+#include "components/metrics/persisted_logs.h"
+
+namespace metrics {
+
+// Interface for recording metrics from PersistedLogs.
+class PersistedLogsMetrics {
+ public:
+  PersistedLogsMetrics() {}
+  ~PersistedLogsMetrics() {}
+
+  virtual PersistedLogs::LogReadStatus RecordLogReadStatus(
+      PersistedLogs::LogReadStatus status) = 0;
+
+  virtual void RecordCompressionRatio(
+    size_t compressed_size, size_t original_size) {}
+
+  virtual void RecordDroppedLogSize(size_t size) {}
+
+  virtual void RecordDroppedLogsNum(int dropped_logs_num) {}
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(PersistedLogsMetrics);
+};
+
+}  // namespace metrics
+
+#endif  // COMPONENTS_METRICS_PERSISTED_LOGS_METRICS_H_