Remove std::string histogram name from HistogramBase object.

base/metrics/persistent_histogram_allocator.cc

 // 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.
 
 #include "base/metrics/persistent_histogram_allocator.h"
 
 #include <memory>
 
 #include "base/atomicops.h"
 #include "base/files/file_path.h"
@@ skipping 622 matching lines @@
   // A second delayed allocations is defined using the same reference storage
   // location as the first so the allocation of one will automatically be found
   // by the other. Within the block, the first half of the space is for "counts"
   // and the second half is for "logged counts".
   DelayedPersistentAllocation logged_data(
       memory_allocator_.get(), &histogram_data_ptr->counts_ref,
       kTypeIdCountsArray, counts_bytes, counts_bytes / 2,
       /*make_iterable=*/false);
 
   // Create the right type of histogram.
-  std::string name(histogram_data_ptr->name);
+  const char* name = histogram_data_ptr->name;
   std::unique_ptr<HistogramBase> histogram;
   switch (histogram_type) {
     case HISTOGRAM:
       histogram = Histogram::PersistentCreate(
           name, histogram_minimum, histogram_maximum, ranges, counts_data,
           logged_data, &histogram_data_ptr->samples_metadata,
           &histogram_data_ptr->logged_metadata);
       DCHECK(histogram);
       break;
     case LINEAR_HISTOGRAM:
@@ skipping 393 matching lines @@
 }
 
 // static
 FilePath GlobalHistogramAllocator::MakeMetricsFilePath(const FilePath& dir,
                                                        StringPiece name) {
   return dir.AppendASCII(name).AddExtension(
       PersistentMemoryAllocator::kFileExtension);
 }
 
 }  // namespace base