Split a MetricsLogStore object out of MetricsLogManager.

components/metrics/metrics_log_store.h

Index: components/metrics/metrics_log_store.h
diff --git a/components/metrics/metrics_log_store.h b/components/metrics/metrics_log_store.h
new file mode 100644
index 0000000000000000000000000000000000000000..b9658d67e6d38010f72c1734da7180c69cb9dde7
--- /dev/null
+++ b/components/metrics/metrics_log_store.h
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+// 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_METRICS_METRICS_LOG_STORE_H_
+#define COMPONENTS_METRICS_METRICS_LOG_STORE_H_
+
+#include <string>
+
+#include "base/macros.h"
+#include "components/metrics/log_store.h"
+#include "components/metrics/metrics_log.h"
+#include "components/metrics/persisted_logs.h"
+
+class PrefService;
+class PrefRegistrySimple;
+
+namespace metrics {
+
+// A LogStore implementation for storing UMA logs.
+// This implementation keeps track of two types of logs, initial and ongoing,
+// each stored in PersistedLogs.  It prioritizes staging initial logs over
+// ongoing logs.
+class MetricsLogStore : public LogStore {
+ public:
+  // Constructs a MetricsLogStore that persists data into |local_state|.
+  // If max_log_size is non-zero, it will not persist ongoing logs larger than
+  // |max_ongoing_log_size| bytes.
+  MetricsLogStore(PrefService* local_state, size_t max_ongoing_log_size);
+  ~MetricsLogStore();
+
+  // Registers local state prefs used by this class.
+  static void RegisterPrefs(PrefRegistrySimple* registry);
+
+  // Saves |log_data| as the given type.
+  void StoreLog(const std::string& log_data, MetricsLog::LogType log_type);
+
+  // LogStore:
+  bool has_unsent_logs() const override;
+  bool has_staged_log() const override;
+  const std::string& staged_log() const override;
+  const std::string& staged_log_hash() const override;
+  void StageNextLog() override;
+  void DiscardStagedLog() override;
+  void PersistUnsentLogs() const override;
+  void LoadPersistedUnsentLogs() override;
+
+  // Inspection methods for tests.
+  size_t ongoing_log_count() const { return ongoing_log_queue_.size(); }
+  size_t initial_log_count() const { return initial_log_queue_.size(); }
+
+ private:
+  // Tracks whether unsent logs (if any) have been loaded from the serializer.
+  bool unsent_logs_loaded_;
+
+  // Logs stored with the INITIAL_STABILITY_LOG type that haven't been sent yet.
+  // These logs will be staged first when staging new logs.
+  PersistedLogs initial_log_queue_;
+  // Logs stored with the ONGOING_LOG type that haven't been sent yet.
+  PersistedLogs ongoing_log_queue_;
+
+  DISALLOW_COPY_AND_ASSIGN(MetricsLogStore);
+};
+
+}  // namespace metrics
+
+#endif  // COMPONENTS_METRICS_METRICS_LOG_STORE_H_