Merge subprocess metrics into global StatisticsRecorder.

base/metrics/persistent_histogram_allocator.h

 // Copyright 2016 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 BASE_METRICS_HISTOGRAM_PERSISTENCE_H_
 #define BASE_METRICS_HISTOGRAM_PERSISTENCE_H_
 
 #include <map>
 #include <memory>
 
@@ skipping 230 matching lines @@
       int maximum,
       const BucketRanges* bucket_ranges,
       int32_t flags,
       Reference* ref_ptr);
 
   // Finalize the creation of the histogram, making it available to other
   // processes if |registered| (as in: added to the StatisticsRecorder) is
   // True, forgetting it otherwise.
   void FinalizeHistogram(Reference ref, bool registered);
 
+  // Merges the data in a persistent histogram with one held globally by the
+  // StatisticsRecorder, updating the "logged" samples within the passed
+  // object so that repeated merges are allowed.
+  void MergeHistogramToStatisticsRecorder(HistogramBase* histogram);
+
   // Returns the object that manages the persistent-sample-map records for a
   // given |id|. Only one |user| of this data is allowed at a time. This does
   // an automatic Acquire() on the records. The user must call Release() on
   // the returned object when it is finished with it. Ownership stays with
   // this allocator.
   PersistentSampleMapRecords* UseSampleMapRecords(uint64_t id,
                                                   const void* user);
 
   // Create internal histograms for tracking memory use and allocation sizes
   // for allocator of |name| (which can simply be the result of Name()). This
@@ skipping 174 matching lines @@
 
   // The location to which the data should be persisted.
   FilePath persistent_location_;
 
   DISALLOW_COPY_AND_ASSIGN(GlobalHistogramAllocator);
 };
 
 }  // namespace base
 
 #endif  // BASE_METRICS_HISTOGRAM_PERSISTENCE_H_