Merge multiple histogram snapshots into single one for reporting.

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_
 
 #include <stdint.h>
 
 #include <map>
+#include <set>
 #include <string>
 #include <vector>
 
 #include "base/gtest_prod_util.h"
 #include "base/macros.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/scoped_vector.h"
 #include "base/memory/weak_ptr.h"
 #include "base/metrics/field_trial.h"
 #include "base/metrics/histogram_flattener.h"
@@ skipping 42 matching lines @@
     UNINITIALIZED_PHASE = 0,
     START_METRICS_RECORDING = 100,
     CREATE_PROFILE = 200,
     STARTUP_TIMEBOMB_ARM = 300,
     THREAD_WATCHER_START = 400,
     MAIN_MESSAGE_LOOP_RUN = 500,
     SHUTDOWN_TIMEBOMB_ARM = 600,
     SHUTDOWN_COMPLETE = 700,
   };
 
+  typedef std::set<base::HistogramBase*> HistogramSet;

[Alexei Svitkine (slow), 2016/02/18 15:47:40]

Doesn't seem like this is used anywhere in this CL?

[bcwhite, 2016/02/18 17:07:05]

Removed.

+
   // Creates the MetricsService with the given |state_manager|, |client|, and
   // |local_state|.  Does not take ownership of the paramaters; instead stores
   // a weak pointer to each. Caller should ensure that the parameters are valid
   // for the lifetime of this class.
   MetricsService(MetricsStateManager* state_manager,
                  MetricsServiceClient* client,
                  PrefService* local_state);
   ~MetricsService() override;
 
   // Initializes metrics recording state. Updates various bookkeeping values in
@@ skipping 398 matching lines @@
   // Weak pointers factory used for saving state. All weak pointers managed by
   // this factory are invalidated in ScheduleNextStateSave.
   base::WeakPtrFactory<MetricsService> state_saver_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(MetricsService);
 };
 
 }  // namespace metrics
 
 #endif  // COMPONENTS_METRICS_METRICS_SERVICE_H_