Revise system profile prefs clearing

components/metrics/metrics_log.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.
 
 // This file defines a set of user experience metrics data recorded by
 // the MetricsService.  This is the unit of data that is sent to the server.
 
 #ifndef COMPONENTS_METRICS_METRICS_LOG_H_
 #define COMPONENTS_METRICS_METRICS_LOG_H_
 
@@ skipping 69 matching lines @@
   static int64_t GetCurrentTime();
 
   // Records a user-initiated action.
   void RecordUserAction(const std::string& key);
 
   // Record any changes in a given histogram for transmission.
   void RecordHistogramDelta(const std::string& histogram_name,
                             const base::HistogramSamples& snapshot);
 
   // Records the current operating environment, including metrics provided by
-  // the specified set of |metrics_providers|.  Takes the list of installed
-  // plugins, Google Update statistics, and synthetic trial IDs as parameters
-  // because those can't be obtained synchronously from the UI thread.
-  // A synthetic trial is one that is set up dynamically by code in Chrome. For
-  // example, a pref may be mapped to a synthetic trial such that the group
-  // is determined by the pref value.
+  // the specified set of |metrics_providers|.  Takes the list of synthetic
+  // trial IDs as a parameter. A synthetic trial is one that is set up
+  // dynamically by code in Chrome. For example, a pref may be mapped to a
+  // synthetic trial such that the group is determined by the pref value.
   void RecordEnvironment(
       const std::vector<MetricsProvider*>& metrics_providers,
       const std::vector<variations::ActiveGroupId>& synthetic_trials,
       int64_t install_date,
       int64_t metrics_reporting_enabled_date);
 
   // Loads the environment proto that was saved by the last RecordEnvironment()
-  // call from prefs and clears the pref value. On success, returns true and
-  // |app_version| contains the recovered version. Otherwise (if there was no
-  // saved environment in prefs or it could not be decoded), returns false and
-  // |app_version| is empty.
+  // call from prefs. On success, returns true and |app_version| contains the
+  // recovered version. Otherwise (if there was no saved environment in prefs
+  // or it could not be decoded), returns false and |app_version| is empty.
   bool LoadSavedEnvironmentFromPrefs(std::string* app_version);
 
   // Writes application stability metrics, including stability metrics provided
   // by the specified set of |metrics_providers|. The system profile portion of
   // the log must have already been filled in by a call to RecordEnvironment()
   // or LoadSavedEnvironmentFromPrefs().
   // NOTE: Has the side-effect of clearing the stability prefs..
   //
   // If this log is of type INITIAL_STABILITY_LOG, records additional info such
   // as number of incomplete shutdowns as well as extra breakpad and debugger
@@ skipping 84 matching lines @@
   const base::TimeTicks creation_time_;
 
   PrefService* local_state_;
 
   DISALLOW_COPY_AND_ASSIGN(MetricsLog);
 };
 
 }  // namespace metrics
 
 #endif  // COMPONENTS_METRICS_METRICS_LOG_H_