Cleanup: Pass std::string as const reference if possible

google_apis/gcm/monitoring/gcm_stats_recorder.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 GOOGLE_APIS_GCM_MONITORING_GCM_STATS_RECORDER_H_
 #define GOOGLE_APIS_GCM_MONITORING_GCM_STATS_RECORDER_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 34 matching lines @@
   virtual void RecordCheckinInitiated(uint64 android_id) = 0;
 
   // Records that a check-in has been delayed due to backoff.
   virtual void RecordCheckinDelayedDueToBackoff(int64 delay_msec) = 0;
 
   // Records that a check-in request has succeeded.
   virtual void RecordCheckinSuccess() = 0;
 
   // Records that a check-in request has failed. If a retry will be tempted then
   // will_retry should be true.
-  virtual void RecordCheckinFailure(std::string status, bool will_retry) = 0;
+  virtual void RecordCheckinFailure(const std::string& status,
+                                    bool will_retry) = 0;
 
   // Records that a connection to MCS has been initiated.
   virtual void RecordConnectionInitiated(const std::string& host) = 0;
 
   // Records that a connection has been delayed due to backoff.
   virtual void RecordConnectionDelayedDueToBackoff(int64 delay_msec) = 0;
 
   // Records that connection has been successfully established.
   virtual void RecordConnectionSuccess() = 0;
 
@@ skipping 65 matching lines @@
                                       int ttl) = 0;
   // Records that a 'send error' message was received.
   virtual void RecordIncomingSendError(const std::string& app_id,
                                        const std::string& receiver_id,
                                        const std::string& message_id) = 0;
 };
 
 }  // namespace gcm
 
 #endif  // GOOGLE_APIS_GCM_MONITORING_GCM_STATS_RECORDER_H_