Basic UkmService implementation

components/metrics/persisted_logs_metrics.h

 // 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 ~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_