Add a histogram to measure number of synthetic UMA trials.

components/metrics/metrics_service.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 service that collects information about the user
 // experience in order to help improve future versions of the app.
 
 #ifndef COMPONENTS_METRICS_METRICS_SERVICE_H_
 #define COMPONENTS_METRICS_METRICS_SERVICE_H_
 
@@ skipping 346 matching lines @@
   void RecordBooleanPrefValue(const char* path, bool value);
 
   // Returns a list of synthetic field trials that were active for the entire
   // duration of the current log.
   void GetCurrentSyntheticFieldTrials(
       std::vector<variations::ActiveGroupId>* synthetic_trials);
 
   // Creates a new MetricsLog instance with the given |log_type|.
   scoped_ptr<MetricsLog> CreateLog(MetricsLog::LogType log_type);
 
+  // Records the current environment (system profile) in |log|.
+  void RecordCurrentEnvironment(MetricsLog* log);
+
   // Record complete list of histograms into the current log.
   // Called when we close a log.
   void RecordCurrentHistograms();
 
   // Record complete list of stability histograms into the current log,
   // i.e., histograms with the |kUmaStabilityHistogramFlag| flag set.
   void RecordCurrentStabilityHistograms();
 
   // Manager for the various in-flight logs.
   MetricsLogManager log_manager_;
@@ skipping 86 matching lines @@
   FRIEND_TEST_ALL_PREFIXES(MetricsServiceTest,
                            PermutedEntropyCacheClearedWhenLowEntropyReset);
   FRIEND_TEST_ALL_PREFIXES(MetricsServiceTest, RegisterSyntheticTrial);
 
   DISALLOW_COPY_AND_ASSIGN(MetricsService);
 };
 
 }  // namespace metrics
 
 #endif  // COMPONENTS_METRICS_METRICS_SERVICE_H_