Make MetricsService save compressed logs to local state.

components/metrics/metrics_log_manager.h

 // Copyright 2014 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_MANAGER_H_
 #define COMPONENTS_METRICS_METRICS_LOG_MANAGER_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 73 matching lines @@
   // This should only be called if there is not a current log.
   void ResumePausedLog();
 
   // Saves the staged log, then clears staged_log().
   // If |store_type| is PROVISIONAL_STORE, it can be dropped from storage with
   // a later call to DiscardLastProvisionalStore (if it hasn't already been
   // staged again).
   // This is intended to be used when logs are being saved while an upload is in
   // progress, in case the upload later succeeds.
   // This can only be called if has_staged_log() is true.
-  void StoreStagedLogAsUnsent(metrics::PersistedLogs::StoreType store_type);
+  void StoreStagedLogAsUnsent(PersistedLogs::StoreType store_type);
 
   // Discards the last log stored with StoreStagedLogAsUnsent with |store_type|
   // set to PROVISIONAL_STORE, as long as it hasn't already been re-staged. If
   // the log is no longer present, this is a no-op.
   void DiscardLastProvisionalStore();
 
   // Saves any unsent logs to persistent storage.
   void PersistUnsentLogs();
 
   // Loads any unsent logs from persistent storage.
   void LoadPersistedUnsentLogs();
 
  private:
-  // Saves |log| as the given type.
-  // NOTE: This clears the contents of |log| (to avoid an expensive copy),
-  // so the log should be discarded after this call.
-  void StoreLog(std::string* log, MetricsLog::LogType log_type);
+  // Saves |log_data| as the given type.
+  void StoreLog(const std::string& log_data, MetricsLog::LogType log_type);
 
   // Tracks whether unsent logs (if any) have been loaded from the serializer.
   bool unsent_logs_loaded_;
 
   // The log that we are still appending to.
   scoped_ptr<MetricsLog> current_log_;
 
   // A paused, previously-current log.
   scoped_ptr<MetricsLog> paused_log_;
 
   // Logs that have not yet been sent.
-  metrics::PersistedLogs initial_log_queue_;
-  metrics::PersistedLogs ongoing_log_queue_;
+  PersistedLogs initial_log_queue_;
+  PersistedLogs ongoing_log_queue_;
 
   DISALLOW_COPY_AND_ASSIGN(MetricsLogManager);
 };
 
 }  // namespace metrics
 
 #endif  // COMPONENTS_METRICS_METRICS_LOG_MANAGER_H_