Split a MetricsLogStore object out of MetricsLogManager.

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
index 1d98413adc2a68f553e31b214b104eec4e899090..e3c58dd1c56b59f6c49a35d20a22de3f06195619 100644
--- a/components/metrics/persisted_logs_metrics.h
+++ b/components/metrics/persisted_logs_metrics.h
@@ -13,11 +13,28 @@ 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) {}