Split a MetricsLogStore object out of MetricsLogManager.

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:
+  // Used to produce a histogram that keeps track of the status of recalling
+  // persisted per logs.
+  enum LogReadStatus {
+    RECALL_SUCCESS,         // We were able to correctly recall a persisted log.
+    LIST_EMPTY,             // Attempting to recall from an empty list.
+    LIST_SIZE_MISSING,      // Failed to recover list size using GetAsInteger().
+    LIST_SIZE_TOO_SMALL,    // Too few elements in the list (less than 3).
+    LIST_SIZE_CORRUPTION,   // List size is not as expected.
+    LOG_STRING_CORRUPTION,  // Failed to recover log string using GetAsString().
+    CHECKSUM_CORRUPTION,    // Failed to verify checksum.
+    CHECKSUM_STRING_CORRUPTION,     // Failed to recover checksum string using
+                                    // GetAsString().
+    DECODE_FAIL,                    // Failed to decode log.
+    DEPRECATED_XML_PROTO_MISMATCH,  // The XML and protobuf logs have
+                                    // inconsistent data.
+    END_RECALL_STATUS  // Number of bins to use to create the histogram.
+  };
+
   PersistedLogsMetrics() {}
   virtual ~PersistedLogsMetrics() {}
 
-  virtual PersistedLogs::LogReadStatus RecordLogReadStatus(
-      PersistedLogs::LogReadStatus status) = 0;
+  virtual void RecordLogReadStatus(LogReadStatus status){};
 
   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_